I really look at this topic a bit differently.
I find that on a daily basis I am referring to my "bucket list," or things I plan on doing in my life before I die.
So, my "I wish I had done this" is really more of a "I still plan to do this."
Travel - specifically to Eastern Asia, all of Europe, the Safaris in Africa, and numerous locations in South America (temples, the Amazon Rain Forrest, Machu Picchu, etc).
I guess this does classify as an "I wish I had done" back when I wouldn't have been the one footing the bill.
C'est la vie - there's not way in heck my parents would have afforded that or allowed me to go without supervision anyway.