Well, my advice can only come in the form of what I have done.
I own a Champion 6800 watt gas unit...peak surge of 7500watts.
The reason I went with something this size is that my plan is to use it for a couple hours a day just to run 2 fridges, 1 chest freezer, my well pump, and to recharge a few items. The size was needed to run all of this at the same time, but not for a long time.
As for heating, generators are not a good way to go. Given the wattage used by electric heaters, you will run through a lot of fuel quickly.
I would suggest a wood stove, but you could also use propane space heaters if that is too big of an installation for you.
As for the Champion brand, I have never had a problem starting it either with the electric start or the pull cord...first pull every time.
I did have a problem once, and could not start it...turned out the fuel valve was closed, and the customer service was excellent!
They suggested that the low oil indicator was faulty, and had perfect instructions to disable it right over the phone!
Of course, when I realized the problem and opened the valve...first pull as usual!
The one issue with these gas powered gennies is the noise, which I plan on muffling by putting it in a dedicated shed, exhausted to the outside with an old muffler from a quad or whatever I can find at the scrap yard.
Hope some of this helps.

OK this is an old subject but, we'll go thru it again. Unless you plan to use this generator every day, the cheaper one will do. I bought one over two years ago, I have never had the need to run it so far, and until the need come, I will not start it up. WHY? you ask!. Well, here it is. Before the generator leaves the factory, the engine is run dry of fuel and a preservative is put into the fuel line and the oil tank. Fuel left in the lines will separate after a time will separate and shellac will coat and clog the lines. So, if you need to run it, do so, but when your done, drain it, run it dry, preserve it, and clean the spark plug. I hope that this helps in your decision on what you need to buy. Oh and don't for get to buy the cables you'll need to get the house and distribute the power.

For occasional use, yup the champion is as good as any. We have one at school and like Denob says, starts first pull every time when fuel is on. (Students forget to turn on) And yes, when you are done, turn fuel off and run it out before storing it for the above mentioned reasons.
The downside with these gen sets is that they are not made for prolonged running. Small oil sump, no oil filter etc so oil level must be checked regularly and changed regularly. They normally run at close to 3600 rpm so "whole life" will be relatively short.
For one that you would intend on running extended periods of time with higher loads, then I'd suggest spending the bucks and get one that will run at 1800 rpm. Kubota or Yanmar makes nice ones. Even seen Lister systems for under 10k but that's a lot of money for just in case.

Denob - to silence the exhaust you can use the rigid pipe insulation. Works real good. We had machines working in cottage country and with the Detroits screaming all night long, an insulated shack and exhaust going into a garbage can lined with large diameter insulation allowed the cottagers to sleep like babies!!

I have 2 gas generators: a 3500 watt Homelite and a 10,000 watt 'commercial type' with electric 'key' start or pull start. This big puppy can run my entire house like normal - we just turn off the main breaker (even if the power is already off) and 'back feed' it via special wiring/panel to the main breaker. My late husband wired everything up and had it inspected. An electrician can do this for you. I store it inside my woodshed and haul it outside when in use so it's not terribly noisy near the house. Never run a generator inside, even inside the garage. HOWEVER, some electronics are 'sensitive' to generator power.
My small genny is for lending out to family and neighbours who STILL aren't prepared. I have 6 -50 foot lengths of heavy duty extention cords. Don't be cheap - buy the heavy duty cord.
Like Denob said, the surge of a well pump turning on (or major appliances) can be significant so choose a generator that can handle this surge.

Caution Please!

If you connect your generator to the house panel do it properly. Have an electrician install a transfer switch and make sure the installation is inspected.

A lot of people back feed the power panel through a suicide cord that plugs into a stove or dryer outlet.

It is called a suicide cord because it can kill. It is possible for the generator power to back feed into the power lines, back feed through the transformer on the pole and kill your friendly hydro worker with a family.

Can you live with that? Don’t do it!

BTW worked in the electrical field for 40 years.

HTP

Admittedly, I don't know a whole lot about generators, but...
I've been looking at an emergency back-up generator for myself. I have an experienced prepper friend that bought a Yamaha tri-fuel unit. It can run on natural gas, propane or gasoline. In an emergency you never know what fuel may not be available, so this unit seems like a good choice. They're not cheap though, which is why I don't have one yet. It is however on my list.

Edit:
Something I remember my friend said. "Propane fuel will store indefinitely with no need to rotate like gasoline".

Thanks for all the info. Like Denob noted, a wood stove/propane heater is more efficient/practical. I think a generator is more of a stop gap for temporary outages, or a couple days without power. I would rather have a generator hooked up in the garage feeding power for a day than chancing a propane burner in the house where there is still a potential for suffocation. We have propane heaters ready for severe cold, and the wood fire place goes in this summer...when it's cheaper to install! XD But I still like the idea of having electricity available. I like your concept of running fridges/freezers for shorter periods...this makes a lot of sense and never thought of that.

I was looking into the larger generators which switch gear that automatically start when power is interrupted. This wasn't my original intent, but has caught my eye after Prepher posted about it. After the initial supply and installation, is there much in the sense of upkeep? testing? Prepher, can you speak more to what unit you have, any ongoing maintenance or costs and whether its worth it? Thnx.

For very short outages, I'd personally go with an inverter and my vehicle. Check this out http://www.solar1234.com/ and listen to the podcasts.

I was skeptical at first (being an auto tech for a time) but I've since done this on a 'test' and I'll be darned if it don't work like a charm. I ran my fridge and a couple of lights for a couple of hours on idle, so it's just as suitable for an LED light or two and a space heater or equivalent. It's easily done and relatively inexpensive, especially if you get the inverter on sale.

I have a generator as well (Personally I'd say stay away from the Champion stuff. I've experienced that the engines on them are decent, but the generator/inverters on them are pretty crap. They are cheap enough though, and I'm sure there are others that swear by them), but I so rarely use it over the vehicle/inverter method I'm planning on storing the gen up on my farm instead.

All in all, mileages may vary and what works for one is different for another I would guess.

If you want some ideas about building your own off-grid energy strategy, this site from Oregon has useful ideas.

http://theepicenter.com/power_sources_generators_and_batteries.html

A 10 horse motor can put out 10 hp or 7500 watts. A 15 hp motor can put out 10 hp or 7500 watts easily without worrying about overheating and it will last longer doing so. A bigger engine will need more fuel. What it will come down to is you need enough Watts to run your house but not oversized so it costs you an arm and a leg to keep fueled.

When sizing a generator keep in mind that fridges, air conditioners and electric motors need a few seconds to start in which they draw much more current than under normal running operation. Say for example you have a 2 horsepower well pump you need to run. 2 horsepower pump is 746watts times 2, so 1500 watts. An 1500 watt generator will not work because motors are not 100% efficient, small motors guesstimate at 50% efficiency, large ones at 75%, meaning it will take 2100 watts of electricity to get 1500watt/2hp mechanical energy out of the motor. To start that motor especially under load it would take even more current (watts =volts xcurrent) because a motor is basically a big load until it comes up to speed- which is why when an air conditioner starts you can sometimes see the lights dim. Figure twice rated full load current from the nameplate of the machine you're trying to start.

It gets confusing very fast. Bare with me

So a 2 hp motor is roughly 1500 watts and you'll need a 3000 watt generator to start it. A heavier rotating mass generator will have more inertia or reciprocating (kinetic) energy to keep it from bogging down or stalling.

Now if you're considering a cheap Chinese junk generator for 399 instead of a professional one like a Honda for 1500 what do you get? Will it start? Sure. Reliable? Maybe. Parts and service if it brakes? Hahaha

I worked for united rentals when I was younger. A Honda equipment could sit on the floor for six months and usually start with the first pull. Is your champion going to do that? Is your wife strong enough to keep yanking on the pull cord fast enough to start the cheap generator? If you're not home can she start the generator to run the sump pump if your basement is starting to flood?

If you're buying a piece of equipment that is necessary dont cheap out. If budget won't allow for new I would still buy a gently used Honda I've a new cheap brand generator. Sure you can get all the parts for your cheap generator off the Internet but if the voltage regulator burns out can you get one in the middle of a hurricane?