FUN, FUN, FUN is to be expected! We went for the first time in September and DQ became an instant favorite for everybody in the family (we ranged in age from my DD5 to my MIL).
There was just something about playing Pac-Man "free" for hours on end. I had a good time learning to draw Pluto (I did an awful job!).
Our biggest mistake was not getting to DQ earlier in the day. We did get there by 5:00 or so, but it wasn't long before the crowd started arriving. I'd say go right after lunch and make a day out of it.