My wife and I rented a Class C motorhome in Salt Lake City and drove to Yellowstone back in mid June of 2010. It was a great way to see the park since you never had to leave the park. We rented a small 22' Class C from Access RV in Salt Lake City for 7 days. Breaking down and leaving the campsite wasn't really an issue since we stayed in Canyon Village and Madison campgrounds which have no hookups. The small class C was easy to park and get around in. I had no issues at all parking anywhere I wanted to as the C was about the length of a large church van. You probably would need to get something bigger for 5 people. In Canyon, they had a nice shower facility for $3 a shower (back in 2010). We never used the motor home shower and there as a dump station and water fill right when you entered the campground.
It might be too late to reserve sites now in Canyon and Madison but they have several campgrounds that are first come first serve. We made reservations for Canyon and Madison as early as was allowed. We are talking about doing this same trip next summer.
The only downside to flying out and renting (we flew in from Florida to Salt Lake City) was they nickle and dime you to death. $$ a day for pots and pans, sheets, etc. We ended up stopping at a Walmart and buying a pot and pan and a few cheap kitchen items. It was much cheaper than paying the daily rental fees.
Burch
