BW is probably a hair closer to the Swan (and YC a hair closer to the dolphin) but they're pretty equidistant, maybe a minute or so difference. If it is hot/humid I find I prefer to catch the boat heading to Epcot and get off at the first stop (Yacht/Beach) to save myself a quarter mile or so, especially if I see the boat loading (which half the time when I went by, it was). But since I'm lazy I take the S/D bus to MK and just hop on the ferry, and then use the Yacht/Beach/BW bus when heading back to avoid going to the TTC. Provided you don't have a long wait for the S/D bus or ferry/monorail it's about a half hour trip from the S/D to entering MK. It's 10-15 from the Boardwalk area resorts to MK but then once you factor 10 minutes to get to the bus stop, then time waiting at the bus stop, it does end up being a bit of a wash in the end. I did like taking the Disney bus back to S/D since I usually leave near close when the ferry/monorail line to the TTC is lengthy.