We've done "parties" three different times. The first two we just grabbed some dinner at a counter service and kept going... this past December we had ADRs for dinner (at 3:30pm) at Crystal Palace.
I don't think it was worth it to waste our time in the Magic Kingdom with a sit down meal. Next time we will just grab counter service again!
We did LTT before MVMCP in 2004 (sorry so long ago) and we are going back again this year on December 4th. It was my DH's favorite character meal. We had a VERY early ADR-- I think it was 4:50. It was really nice.. the restaurant wasn't as crowded and there seemed to be fewer kids for some reason-- meaning, ours got lots of attention from the characters! We weren't there terribly long and the five characters were at our table two times a piece plus two of them made it around three times!