We prefer to have our own car when staying at Disney as it is a HUGE time saver. One year in June, it took 1.5 hours to get from POFQ to dinner at Ohana on the bus. We missed our ADR and had to wait for a free table- and they only let us do this because it was our anniversary dinner (they actually were booked but took us anyway). It's also much faster to use your own transportation if you are park hopping. I guess a big part of having our own vehicle is that many of the restaurants we prefer are at resort hotels; it'd take a lot longer for us to use Disney transportation rather than have our own car... and at Disney, time=money!