Without wishing to appear too narcisstic, I'd quite like to have a conversation with the seven year old me. It'd be really interesting to see how you'd changed, and if you liked the younger you.
I've always made an effort to tell my nearest and dearest what I wanted them to know, and I consider myself lucky in that regard, but if time travel wan't an obstacle I'd love to have a conversation with my eight great grandparents, none of whom I knew, but I know quite a lot about them, and it would be interesting to form my own opinion of them.