power Cords/Cables

I agree that 50 amp is very common. But get a 50 amp female to 30 amp male adapter and a 30 amp female to 20 amp male adapter. That covers all your bases. We have camped several times at a park in Colorado that only had 20 amp available. But at over 8,500', even in summer it is cool enough not to need A/C.

A 50 amp extension cord is not a bad idea either. Sometimes the power post is not in the best location to center your rig in your site without extra cord. Same goes for extra water hose and sewer hose.