Depending on where your room is located it might be closer to walk to Beach Club and take their bus to Magic Kingdom. Both of those are closer than walking to Hollywood Studios though.
GF security won't let guests in uber/lyft in to drop off without the guest having a dining, recreation or resort reservation.
OP, I would walk to YC from the Dolphin (YC is closer than BWI) and take the bus from there. On the way back, grab whichever bus comes first - YC/BC or BWI.