I was lucky enough to meet Mr. Davis when he made his only (as far as I know) appeariance at The Wizard World show in Chicago. I think this was back in 1996. He was signing at the DC booth, and had a fairly long line waiting to meet him.
I was fortunate enough to have him sign Issue #1 of Excalibure, Batman Full Circle, and The Nail # 1.
Mr. Davis has been my favorite artist since his work on Detective, and I had been looking forward to getting to meet him since they had announced he would be a guest. I finaly got up there to meet him and I'm sure I must have come off as the dumbest American he had ever met.
I think I asked how he liked Chicago and I probably gushed about how much I enjoy his work, with a goofy smile on my face. For his part, he was very gracious and I think he said somthing nice about Chicago.
At the end of the day I wound up in the hospital with what turned out to be severe food poisoning.
The only reason I mention this is the fact that before I was diagnosed, I was afraid that I had some horrible virus and that I might have given it to him when i shook his hand that afternoon. I didn't want to be known as the man who gave Mr. Davis the plague.
Aside from that part it was my favorite convention ever.

I don't know what I regret, So I guess I regret not knowing.