When I stayed onsite and even when I had a car, I never felt stuck at Universal. Even if you do feel stuck, you can take a taxi to nearby I-Drive and see all the stuff going on there. I-Drive in itself is an experience!
Transportation and proxcimity work so well together in Orlando that you will be more than fine... Orlando's tansportation (I-ride, taxi, hotel trans) is extremely efficien for what it is.
I have always wanted to be able to "just hang out" at the HRH, but never have had the time. We usually can't tear ourselves away from the parks!! The only time we've used our car is when we went to the Kobe steak house for DD's 18th birthday dinner.
Thanks for your input- I think we will be more inclined to relax and have fun if we don't have a car tempting us to find out "what else is out there." We've been to Disney 6 times, so we know what is THERE and not having a car will help us focus on the fun at hand.
Thanks!