We have taken our 23' hybrid trailer down twice now and have had great times! We have not made the trek without the trailer so I can't tell you the difference with gas, but the savings in food has more than made up for it! Because we have planned our trips this way, we have been able to afford 2 weeks at Fort Wilderness, rather than 1 at a value resort. We bring most of our own snacks and drinks to the parks, eat breakfast at the trailer, and one other meal, depending on the day. Since FW has such easy access to MK, it is easy to break up a long day and come back for dinner, a rest, put warm clothes on, and head back for a few more rides and Spectromagic and WIshes. We also love being able to have space to relax - something you don't have a lot of in a hotel room with kids. Even if you are pulling a smaller tent trailer, you can still load it up with more "comfort" items than a suitcase. We used park hopper options for the first time this trip and it worked well for us. We would go to one park until early afternoon, head back to the camper and eat. The kids would play and have a bit of down time, then we would head out again. We did this more on the second week of the holiday, the first week we didn't hop and we spent the entire day at one park.
Our trailer is set up that the kids bed areas fold down and are separate from the main living area, which makes it easier for me to tidy up and organize things for the next day before watching tv or reading while the kids are sleeping. If you don't have that, you can still sit outside in the lawn chairs and enjoy the evening while the kids fall asleep - I think you get the idea. It is the flexibility and savings that we love. Yes, camping is not as cheap as it used to be, but if you look at your overall savings in food etc, you are still ahead of the game.
Fort Wilderness is known as the best campground in America. While I haven't been to too many there, it sure beats anything in Canada hands down that I have been to.