Relaxing boatride
I stayed at the Yacht Club last year, so we took the boat everyday. In my experience it takes about half an hour between Disney Studios and the World Showcase at Epcot. It stops at Swan, Yacht Club, and Boardwalk along the way (and back). Seats were almost always available, and the "Captain" and his/her crew are interesting to talk to. Many of them are older, and on their second careers. One Captain used to run factories on the east coast, and was very interesting. Sit near the front. We also had a younger crew member one night who sang and told jokes. Find that on a bus.
I know not how it compares to buses, but if your dinner reservation is in the World Showcase, the boat is probably faster because it drops you off at the International Gateway between the United Kingdom and France. Less walking. More fun. More unique. More relaxing.