Like Luke we always have a car, onsite or offsite.
Many people visit and have no problems with transport, I just can't get on with it, I don't get on well waiting for buses or sitting on crowded buses. Not been on a bus in UK for about 25 years, I like being in control. Tried a couple of times in Disney but me and buses don't go together.
As Luke says there is more to the area than Disney, we have friends at Hunters Creek, drive to the port for a cruise, day trips to places like Savannah (Georgia), Clearwater, Daytona, Cocoa beach, spend evenings at The Old Town or Celebration, If not on Dining plan we eat a lot at Hunters Creek away from tourist area, Mannys Chophouse @ Haines City.
We also do something called Geocaching
http://www.geocaching.com/ Go out and find caches that have been hidden all over the world, many around central Florida.
Our next trip at Easter I doubt we will even go into Disney so a car is a must for us, others manage without.