How do we know we aren't living in the alternate present of a past changed by someone from the future? We wouldn't know of anything else. You don't wake up in the morning thinking "I'm sure the world blew up yesterday". Wait... it's called a hangover.
I want to go to the past, something I know better than I do the future. Except the past was kind of sucky. The future would be cool to see but could also be terrifying if you find out about some things.
If you go a few hundred years back you could woo the wimmin with your funky clothes and knowledge of computers.