Our first trip to Fort Wilderness was in a rental motorhome, it sure wet our appetite for camping. We really love it, its good for the whole family.
Cruise America is a rather large rental company, they have rental locations all over the USA.
The camping was great, the actual motorhome - well thats another story, we rented from a local man who has about a handfull of "Older" motorhomes he rents out, the price was good but we had some mechanical problems the put a crimp in some of our vacation time. Don't let that scare you though, just be sure to rent from a reputable company and have them thouroughly explain all the functions of the unit you rent. I am sure you will have a great time.