My 50th reunion is a year from now. While a tiny part of me wishes I'd go (or, more accurately, wishes I wanted to go - in which case, I would), I really don't, and shan't. I've never gone to one, and the real regret is that I didn't do it ten or twenty years back when more people I'd actually want to see and spend some time with were participating.
Five years ago I'd just gotten back in touch with a few people and was all for going to the 45th. I even had reservations made (it's in Fort Lauderdale). A couple of weeks before, something else came up -- something minor, in comparison, but a thing that I really wanted to do -- and I thought and thought about it before making my decision. I finally accepted that I liked the IDEA of going more than the reality. I knew who was going to be there, and it honestly wasn't any of the people I'd had anything in common with and would want to spend time with now. So I cancelled, and immediately knew I'd done the right thing. I still stay in touch with them in superficial fashion on Facebook. (It's my one Facebook activity, the only reason I registered and maintain an account.)
I thought then that I'd probably go to the 50th, but my goodness, how time flies and how easy that was to say. But I've followed their plans and there's still no one I'd care to see, so it ain't happening. A small regret...but not a dealbreaker.