The BC/YC/Swan/Dolph/BW area is perfect for running options. Depending on the time of day you're looking, the path from Swan to HS will have people on it, but it's certainly not wall-to-wall people. There is also a bridge partway to HS where you can branch off, go up to the main road, and run on some of the sidewalks they have available around that resort area. The sidewalks will lead you back to the front of the S/D resort. But for me, if you're looking for 2-3 miles, I'd head from Swan to the HS path, find a point around the buses to turn around, and then head back. If you need a little extra distance at the end, turn right at the Boardwalk and take the loop around the lake towards EPCOT, past BC/YC, and back to the Swan. That's going to get you in the 2-3 mile range. It's one of my favorite running loops at WDW.