If you're going to get one, spend a bit and get something in the 5000 watt range. You need to protect not just your snakes, but the contents of your refrigerator/freezer, especially if you have f/t feeders. My generator more than paid for itself when we lost power for four days in July a few years back and the high temperatures topped 100*F every day. My neighbors had to toss hundreds or even thousands of dollars in rotting meat, venison, etc. when the contents of their refrigerators and chest freezers got too warm. We lost nothing.
Make sure you run it outside in a well-ventilated area. Carbon monoxide poisoning is a real danger and it will kill.
Security is another issue. Generators are noisy and my neighborhood had a lot of extra foot and vehicle traffic between midnight and 6:00 a.m. when the power was out for four days. We had to make sure someone was awake at all times to ensure the generator didn't grow legs and walk away...
Also, if you get a more powerful one than you need, you can let your neighbors run an extension cord to it in exchange for helping keep it fueled up, and helping make sure it stays where it's supposed to. Plus, they won't complain about the noise if they're benefitting from it.
Finally, generator power is dirty. Don't plan on running a high-end digital t-stat on it, you're better off just using it to run a space heater to maintain the ambient temp in the snake room. If you have something like an incubator t-stat, make sure it's on a surge protector.