I'd like to imaging I'd go up to them politely, say something along the lines of "hey I'm a fan, and I'd just like to let you guys know I really enjoy your work!" and then stem into a nice conversation.
...I suuuuckkkkk at starting conversations. I'd probably be too shy, or just awkward. I'd get better as the conversation goes on, but I cannot start conversations for the life of me. So, chances are I wouldn't say anything.
Which sucks, 'cause they all seem like really cool people.