Trek Celebrity Autographs/Picture/Etc.

If you've been to a Trek/sci-fi convention, you know the options: You can wait in a long line for a quick photo with your favourite actor/director/writer/etc., you can attend a panel, or you can get an autograph, along with a few seconds of interaction. The trio discusses their past encouters with Trek (and other franchise) celebrities in the autograph line. Who would you like to spend a few moments of coversation with, while leaving with a signed piece of memorabilia? Is there a better system? Let us know about your con experiences!