At least for an hour or two post illuminations the entertainment is running. Its peak Boardwalk time. Do remember that you can't get back to the Epcot front gate if you drove - and that you won't be able to take a bus back to your resort from Epcot after parks have closed (maybe through DTD, but plan on it taking a long time). A cab or Minnie Van would be your best bet.
We recently had a room overlooking BW village green area and things were always bustling until 10-11pm as that's when we'd go to bed and it would still be hopping out there but would quiet down around then. They had movies under the stars for the littles. They have juggler, magician and the carnival games. But the bars are open later and are pretty active.
Be sure to check out AbracadaBar...it is really neat ()magician / 1920s themed bar on the Boardwalk()...we stopped in on our last trip and it was a fun experience