A very romantic weekend trip to Bermuda at a pretty swanky hotel. Many years ago and it was a total surprise to me.
I returned to my car many years ago to find it covered with PostIt notes from one of my co workers. I was flattered to start with, but ultimately we were both rather embarrassed about it (she rather more than me).
It was never mentioned again (and we're still "just good friends").
My girlfriend's existence is the best Valentine itself! She's my Valentine :)