I'll warn you that my suggestions are based on having boys!
I would walk to DTD...go to the
Lego store first. They have tables where the kids can build with Legos...and the monorail runs right outside the window. My boys would be good for nearly an hour! Then, let the kids get the little tubs that they can fill with Lego bits that you can only get at Lego stores. A hint...get more wheels and axels than you ever think you'll need. They are super cheap this way. Take the kids' pictures with Darth Vader while you're there.
Go to ESPN Zone for dinner. I don't know if your they're still offering points on the tickets, but between the points we got that way and the points from joining their MVP Club, my boys played for well over an hour at no extra cost to me! They have mini-bowling, skateboards, skidoos, etc. Lots of cool interactive video stuff we've never seen at home. And, of course, they had the old favorites like air hockey. They have a climbing wall, too. My older son was majorly bummed that it was closed the day we visited.
Do the picture thing with the DCA letters. When we were they had Herbie out, too...maybe they'll have something fun in the plaza area when you're there, too.
Then I'd head back to my hotel for a swim. You should be able to see bits of the fireworks from the pool if you're staying at a nearby hotel.
We left home at 5 am our time...the kids had been up since 4:30. We got there mid-morning and spent the day at the beach. My kids were more than ready for bed by 8...which would have been 10 our time.
I'd suggest that whatever you do, if you have kids, pick activities that let them run and play. Traveling is very boring and sedentary. They won't want to do a quiet walking tour after a day of travel!
On the other hand, if you're traveling with adults, I'd say try the DTD activities geared for adults. There are bars that have entertainment...and the movies someone mentioned.
Just be sure that whatever you do, you get to bed early so you aren't tired for your first day in the parks!
BTW...we stayed at HoJos. I was expecting tv enterainment similar to what you get at WDW (Cartoon Disney and the Disney Channel) and was disappointed they weren't offered, but my kids were thrilled with the channel that previews events and rides at the park. They ended up being more enthusiastic about it than my older son had been about the cartoon channels at WDW! If you have kids they might enjoy 30 minutes or so of "coming events" before they head to bed!