So your second cousin decided to give you a time machine for our birthday. Only problem is, it can only be used for one journey and back. Unless of course, you happen to have some uranium spare. Although I can't imagine the CIA would be at all pleased...
So where would you go? To the past to see what a certain period in time was like? Or to see what the future holds for yourself or into the far distant future.
Or of course. I suppose there's the option where you don't use it.