I have thought long and hard about this, since my answer to this question has always been "I wouldn't change a thing, because all I have I owe to where I've been", but that doesn't hold so true any more.
I would have had more children for certain, although my Amy has always been enough.
I would have spent more time with my Mom and Dad before they passed....God, I miss them every single day. I have no regrets about the quality of our relationships, but I feel cheated out of time with them.
That is all I guess.