I know the feeling! Even if I didn't have the meet and greet at 5, I probably would have still left early. I've been trying to figure out what to say to them, and this is what I think I've decided on:
NOTE: The shirt I refer to with JP is the one I won in the setlist guessing contest last year on here.
JP: Hi John! I discovered you guys through Rock Band 2 and never looked back. I won this shirt in a setlist guessing contest on DreamTheaterForums.org last year, and apparently you gave it to the administrator, so if it would be okay, I'd really like to have you sign it.
If I have time I will also say: Any cool plans for the upcoming DVD, like a Bluray or 3D version? And you guys have to do a commentary, we love those!
JM: It's an honor to meet you John. You played some truly amazing parts on the last album, and I just wanted to thank you for the inspiring lyrics you have written throughout the years.
JR: Hey Jordan! All of the experimentation you've done with the iPad and other instruments is awesome! I really enjoyed your Stageit.com concert and hope you do more of them.
MM: Nice to meet you Mike. I think you are a perfect fit for DT, and you blew my mind last year live in Pittsburgh. I cannot wait to see you killing it out there tonight!
JLB: Hi James! You are an absolute inspiration to me, having chose singing as my particular instrument. I've never sang rock or metal, but I did a couple of plays in high school, playing Riff in West Side Story and Tevye in Fiddler on the Roof. I know you are interested in Broadway as well, and I hope you get the chance to do it someday. BTW, the forklift videos were hilarious!
Hopefully not too longwinded, and I feel somewhat stupid for having it planned out, but I don't want to waste time and/or get flustered.