I think it all depends on what your goal is. My sisters and I went to all four parks in one day Thanksgiving weekend of 2003 because we just wanted to hit all the major attractions We were able to get buses from each park to another, I am sure of it, but maybe they changed things. Anyway we started at MK when it opened and headed right for Splash/Haunted Mansion/Thunder Mountain. THen we went on POC, IASM and Space Mountain.... that might be all we did. We hopped a bus to MGM, did only RNR, ate lunch and headed to Animal Kingdom. THere we only did Dinosaur and It's Tough to be a Bug, and then we got to Epcot around 7, went on Mission Space, and then spent the rest of the night walking around the WS.
I am glad we did it that way because i had never been on any of the rides outside the Magic Kingdom ones and Dinosaur and RNR are now my two favorite rides at Disney! But if the buses won't take you from park to park then I would consider just picking two and taking a cab. As you can see, we really missed a lot of stuff. If you like all the little attractions and to take your time and experience every detail, then just pick one or two. But like I said, if your goal is to go on all the major attractions and some of your old favorites, I definitely think it is possible.
I am glad we did it that way because i had never been on any of the rides outside the Magic Kingdom ones and Dinosaur and RNR are now my two favorite rides at Disney! But if the buses won't take you from park to park then I would consider just picking two and taking a cab. As you can see, we really missed a lot of stuff. If you like all the little attractions and to take your time and experience every detail, then just pick one or two. But like I said, if your goal is to go on all the major attractions and some of your old favorites, I definitely think it is possible.