Transportation is one of many advantages the Polynesian has IMHO. But for dinner at Boardwalk if you won't have a car, then a cab will be fastest and easiest.
I agree about walking to the TTC to get to Epcot.
I think goofy4tink was talking about the resort launch rather than the big ferry that goes from the TTC to the MK? Anyway, the launch supposedly starts at 8:30 but it doesn't always seem to do so in our experience. As much as we love the launch, we usually take the monorail to the MK...tradition I guess. Anyway, we find it rather fast on the way to the MK. You only have one stop at the GF which is usually a short stop. THe resort monorail begins running at 7am. But the launch does go directly from the Polynesian to the MK (and then on to the GF) so if you're close to the pier, it sure is another fun way to travel .
But the ferry itself is very fast. You then have to walk from the TTC but as goofy4tink said, it is a short walk. It is crowded in the am going to the MK but if you return to the Polynesian midday and you're in one of the Eastern longhouses, the ferry can be fun too.
I know the CR and Polynesian most often share a bus to AK & MGM with the Polynesian being the last stop before the park. I don't know how often those buses run. If no one else helps you here, try asking on the transportation board. You can also walk over to the TTC and catch a park bur there too. Those buses run every 20 minutes.