Meeting at the BW shouldn't be a problem. IMHO, the best way to get there from any of the All Star Hotels is to take the bus to MGM and then walk over to the BW. The walk will take you about 15 minutes. There is a very nice paved (and it is well lighted in the evening) walkway along the canal. As WDWTrekker said, there is also a boat. If you take the boat, get off at the first stop - at the Swan/Dolphin. Then just walk over the bridge and you are on the Boardwalk.
Reverse the directions to return to your hotel. Remember that the MGM park must be open to use this route. If they are closed, your only Disney transportation is to take the bus to DD and transfer there. These buses run until either 1 AM or 2 AM. In this situation, though, I'd opt for a cab. It should cost $10 - $12, including tip and will take less than 15 minutes. Going via DD will take more than an hour.
Also, if you walk through EPCOT, you will need park admission. Walking from the EPCOT bus stop to the BW is a longer walk than walking from the MGM bus stop.
Enjoy your trip!