While I'm with the majority in saying I've never really had a bad stage door experience, a couple visits really stand out:
Pamela Isaacs, who played Muzzy in the 2004 Thoroughly Modern Millie National tour. While most of the cast was wonderful and signed both my poster and my program (It was my birthday, after all =)), Ms. Isaacs stayed and chatted with my mother and me about how she got into acting and her experiences and gave me some advice. She was amazing.
Anthony Rapp, (of course) during the LSOH tours. The poor dear looked DREADFULLY tired, but he still stayed to talk with me, my friend, and the couple others who were waiting as well, all of us with some form of Rent memorabilia we wanted signed. He EVEN was willing to take pictures with all of us, and, to my delight, I can now say Anthony Rapp's arm was around me as he sang sweet nothings in my ear.
"Push the button, just push the button, push the button, on the camera, to take the picture, just a button..."
Hey, I'll take what I can! =)
Michael Gruber, who did Singin' in the Rain here in Seattle last January. Probably my BEST stage door experience. I wasn't expecting to see anyone I knew when I went (bought tickets night-of) and, being a former Cats fan, nearly had a heart attack when I saw his name in the program. I was the only one waiting at the door, and got a lot of the cast's autographs thanks to Joey Matta, the show's assistant choreographer, (who also offered me his dance classes, which I'm still bitter I wasn't able to do). After nearly an hour of waiting some backstage hand came out and told me he didn't think anyone was left, but determined, I waited another ten minutes or so, and Michael Gruber, Michael Arnold (Cosmo), and the woman who played Kathy (is it sad how I only remember the guys? I'm a traitor to my own sex!) came out, and they were all, "Wow, someone's actually out here! And we were dragging our butts coming down!" They were all wonderful and talked to me for a good while about acting in general, and my upcoming trip to New York and little hints and what not. There was a big excited livejournal entry when I got home that night, let me tell you.
Oh, now I'm all happy and excited recalling these things. =)
), Sutton Foster - actually all the people from Little Women, Anthony Rapp, Sherie Rene Scott, and probably lots more that I can't think of at this moment. 
