We stay at Boadwalk a lot, and PPs are correct about the time eating. However, it is a really nice ride and I feel will save you some walking. At DHS, you have to walk across the front entrance area to get to the boat launch from the bus stops. Boats run every 20 minutes or so, and sometimes wait a few minutes at each end (Epcot and DHS) to let the boats fill up some more. The ride is pretty, but stops at Swan/Dolphin, then Yacht/Beach Club, then Boardwalk before finally ending up at Epcot.
You could take a bus from your resort to any park, then take a bus to Boardwalk, but that will not save much walking. The walk is less than 10 minutes from Boardwalk to Epcot, but some of it is uphill, and honestly that is probably not much shorter of a walk than you would have from the front entrance to World Showcase.
