Sorry it took me so long to reply - we got home late on 5/31 and I was at work (long hours) for the rest of the week.
We had lunch with astronaut Bob Springer on Saturday 5/29. There were probably 25-30 people there. It was served as a buffet - the same menu as is on the official website. He didn't join us until everyone was finished eating. His part of the meal started with a short, humorous film of astronauts trying various things (eating, games) in zero gravity. After that Col. Springer talked about his two trips aboard the space shuttle (15 minutes or so) and answered questions (10 minutes or so). After that he posed for pictures with anyone who wanted one. Everyone got an autographed picture of the space shuttle taking off. It was nice, but you could have asked him questions at the astronaut encounter sessions open to everyone (not sure if he poses for pictures though). All in all, it was nice, but we probably won't do it again.
The bad thing was that we couldn't go on the tour until after the lunch because we arrived at the space center at 9:45 and the tour takes 2 1/2 hours and we would have been late for lunch (12:15). That meant that we went on the tour in the afternoon with the late arrivers. Much more crowded.
Our favorite part of KSC was the tour and the stop at the Saturn 5 rocket center. You take part in a simulated takeoff of Apollo 8 and the lunar landing of Apollo 11. Both well worth the time.
Enjoy your trip!