Yes. It is a short walk from Swan/Dolphin to the Boardwalk (maybe 5-10 min). Just know that parking at Dolphin is different from the policies at other Disney resorts. I know they charge for parking nightly if you are staying in a room there (which always rubs me the wrong way, for some reason, especially since the regular resorts don't charge). I'm not sure what they do for confirmed dining reservations. It may be free for 3 hours like the others...
Anyway, you should easily be able to do both.