I would bring the Doctor (from Doctor Who) to life for a day. He can travel through time and space in his time machine, the TARDIS, and he knows his way around the universe. What more could an average human being ask for? =) In that one day I'd ask him to bring me to outer space, to see dinosaurs, to Shakespearean times, to the first Olympics, to see my ancestors (I don't know anything about my family history beyond my grandparents), to the future, to...well, everywhere, if there is time.

The good thing about a time machine is that you can take your own sweet time exploring and return back to the present as if you've only been gone a minute. So technically, I will be able to go anywhere I want in a day, haha.