I've had a bit of experience with generators, such as living off of a 1350 Watt surge/1200 Watt continue generator during the Great Ice Storm of 2003 in central Kentucky (4.5 days with no commercial electricity).
One lesson learned is check the size of the fuel tank very carefully. That generator I was using had a half-gallon fuel tank. That was enough to run the generator for about 90 minutes, under full load, before the tank was emptied and it quit. It's not very much fun at all, refueling a generator, multiple times during the night, in sub-freezing weather, while holding a flashlight in your mouth. Oh, and don't even think about "hot fueling" a generator. That's an excellent way to turn yourself into a "crispy critter".
Consider very carefully where you will place the generator. Generators produce Carbon Monoxide, which is poisonous, and will kill you, in a most subtle way. Make sure the generator is far enough away from your vehicle/residence/RV/etc., such that the exhaust will not be blowing Carbon Monoxide into your living space. Know the signs of Carbon Monoxide poisoning (That cherry red glow on your cheeks may be signs of Carbon Monoxide poisoning!), and have a working Carbon Monoxide detector.
Consider your fuel source, and how to safely store/obtain adequate fuel for extended operation of your generator. Note that, during a long-term power outage, gasoline stations won't be able to dispense gasoline. Additionally, a running generator acts as a beacon for all of the fuel thieves within earshot to steal your gasoline. For that matter, there are idiots who will also steal your generator. Make sure you can chain it down, with a heavy log-chain and a secure padlock, to something immovable.
Diesel powered generators may produce more life out of the engine than gasoline generators, given that Diesel engines tend to be built heavier and operate at a slower speed. Finding a Diesel powered generator is difficult to impossible, though. Four pole generators (alternators) require slower rotational speed than two pole generators, but are even harder to find, until you get into the large industrial/military sizes.
Having two generators may be useful, if one is a tiny one and the other is a large one. The small one will, almost certainly, use less fuel than the large one. And, while the small one won't run as many items, the fuel economy may be useful. The larger one, of course, will operate everything all at once, or will operate the heaviest loads.
Induction motors are bad about requiring a high starting surge. Unfortunately, most rotating devices are powered by induction motors (e.g., refrigerators, freezers, air conditioners, blowers, mixers, washing machines, dryers, etc.). Pay attention to the starting surge demands for these devices.
Don't forget that many RVs/Travel Trailers are equipped with refrigerators which will operate either from 117 Volt power, 12 Volt power, or Propane.
Also, don't forget to plan for upgrades. Most smaller/older RVs/Travel Trailers have a 30 Amp/117 Volt connector, while the larger/newer ones have a 50 Amp/234 Volt connector. If you ever plan to upgrade, it may be worth getting a generator which will operate the larger/newer RV/Travel Trailer.
Don't forget to keep a fire extinguisher handy.
Pay attention to electrical grounds. Some generators play fast and loose with grounding. You do not want to turn into a cripsy critter due to grounding issues.
Look into getting a Kill-a-Watt meter, for measuring the actual power consumption of a device. Also, note that some devices are rated in Watts, while others are rated in Volt-Amperes. If the load presents a unity Power Factor (PF), then Watts=Volts x Amperes. However, some devices, such as induction motors, run at a non-unity power factor. Thus, while the number of Watts may be fairly low, the number of Volts x Amperes will be quite a bit higher. Take the worst case, and use that value for sizing the generator.
There's probably a bunch of things I've forgotten about generators, but that should get y'all started.