It might depend on what time of the year you are visiting. We go every October and during that time the boat only goes to Market Place. You then need to walk to PI and West Side. Or if you would rather, you can take the bus to DTD. It makes more than one stop.
Last year, the boat was also making stops at Saratogo Springs. Not sure if they are still doing that or if SSR has their own boat now. We'll find out next month!
When we were there last year in November the boats ran every 30 minutes in the day time and every 20 minutes in the evenings. The boat only had one stop, right by the Rainforest cafe.
When we were there in November 2002, they were running pretty infrequently (I think every 30 minutes). However, everything was pretty slow then; I think they were still feeling the effects of 9/11.