Most of the the resorts the Downtown Disney bus shares with Typhoon Lagoon. So just watch the bus signs and if any of them have DTD and a resort name on the bus, get on!
The closest resorts all have multiple stops internally. OKW has 6 stops, PO has 5 and so does SSR. SSR is closest to DTD so that may be the best. You could also consider POP, although its about 7 minutes away, its one stop there and then right back.