We had ressies for a late lunch this spring break. It wasn't really crowded, but that let our server (and the other servers there) actually be sillier, if that's possible. Since they weren't racing around serving, they interacted more. My trip report (on the TR board) has lots of details. I think it was our next to the last day, so it's toward the bottom of the first page.
But some highlights included:
Our server taking our camera all around the restaurant to get pictures of everyone else (said something about having permanent record of all the people who could testify to our bad behavior).
Another server giving our server a really hard time, and trying to get us in on the action. My kids leapt to Chad's defense, so they got teased too!
The whole straws thrown at you thing.
The pony trot with my mom and I singing happy birthday to DD. They got everyone there in on the action (hence the reason for the witness photos).
I'd say it was plenty of fun, even with fewer people there. So don't worry if you can't get the ADR changed.