We are DVC members at the BWV and bus transportation has been our biggest complaint since day one. There never seems to be a "dedicated" route for the these resorts. Sometimes the bus will pick up only at the BW and then at the S/D. Other times, it will stop at all of the resorts which is a grand total of seven on one bus (BWI, BWV, Swan, Dolphin, YC, BC, BCV). Even at the Value resorts the buses make less stops.
We have found that the transportation is OK to the MK but spotty on the return. AK is a nightmare and we usually just drive there. With AK you have the additional stop at Blizzard Beach and on the return trip, you usually stop at all of the hotels.
If you find yourself on a bus making all of the stops, it is much quicker to get off at the Swan and walk across the bridge to the BW. You will save yourself about 10-15 minutes.
In regards to the boats to MGM, if you miss it at BW and it hasn't reached the YC/BC, you can walk over to the S/D and pick it up there. If it is leaving the YC/BC. you probably won't make it. We usually take the walkway to MGM along the canal. It is about a 10-15 minute walk. At closing, you can usually walk back quicker to the BW then to wait in the line for the boat.