I like the Boardwalk, if for nothing else - it's really pretty at night. It's just a great place to walk around. There is no direct transportation from that are to other resorts, but from MGM or Epcot you can take a boat to the Boardwalk. It is a nice way to arrive (esp. from Epcot). You go out the back exit of Epcot - near the United Kingdom. The walk from Epcot isn't bad either, but the boat is more romantic. After going to the Boardwalk, assuming you aren't headed back to Epcot for the fireworks, you can take the boat to MGM, and it drops you off near the entrance/bus area for the other resorts. Although the buses from MGM will only run an hour after park closing. (Epcot usually closes at 9). You could also take a taxi, which probably wouldn't cost that much. There is also some overflow parking at the Boardwalk for people who are going to dinner there. If you are a resort guest, you can park there, but the overflow lots are a bit of a walk. You could also hop on a bus by the Boardwalk for DTD, but I think this would take longer than some of the other options I listed.
As for closing time, I suspect it might vary by season. We once saw the performers leaving around 10:30, I think it was. I suspect the clubs stay open past midnight.