Kim,
The start for the half is on the "highway" that wraps around the outside of Epcot. It is about 1 mile down the same road as the start for the full marathon. You are corralled that morning in the Epcot Wonder parking lot and then they release each corral to walk over to the outer road around Epcot for the start.
The finish line is the same for both the half and the full. It's in the Wonder parking lot right outside the main gates for Epcot. You actually run around Spaceship Earth, go backstage for a brief few moments, then emerge out into the finish line area in the parking lot with the grandstands, people cheering, music, etc. It's quite overwhelming.
On to your question: really, the only resorts within walking distance of the finish line are the Epcot resorts (BW, BC, YC, Swan, Dolphin), but you have to walk back through Epcot and out the International Gateway to get to those resorts. It's at least a one mile walk from the finish line.
There are a few resorts near the starting line for the half (POFQ, POR, OKW), but they are a further walk to the half start line as opposed to the full, and I've heard reports from last year that Disney security is really trying to keep people from walking to the start from these resorts since you have to cross a road and go over an entrance ramp to the highway. Can any of you guys comfirm this?
Other than that, nothing is within walking distance. And keep in mind that if you do walk back to the Epcot resorts after the race, you'll need admission to the theme parks to get through the main gate.
Hope this helps!
Steve