The best way to go from resort to resort is via taxi. We have used the Mears taxi's with six people and paid the same price as we would for two people. They keep the van taxis standing nearby. You can see them parked by the bus stop. In fact, every time we have used a Mears taxi to go from resort to resort, even if it was just two of us, they have given us the van, although every time is really only about five times.
If you want to use Disney transportation to go from resort to resort, then you have to take a resort bus from a park to do it. We prefer to pick up a resort bus at DHS rather than Epcot because the DHS bus depot is very close to the walkway and boat dock. The resort bus stop at Epcot is a bit of a distance and we found out that it is just as far to walk through Epcot as it is to walk to DHS.
We have gone to Trail's End from BC via two different ways: one was the MK bus to FW boat, the other was a taxi to the Wilderness Lodge with a nice stop at the Territory Lounge, and then a lovely walk on the nature path to FW. We saw deer on the way there and stopped to see the horses before our ADR. The second way was definitely our favorite way to go. In fact, we booked another ADR at Trails End in October and will be stopping by the WL again.