I would travel into the past. The way I look at it: if you travel into the future, you are skipping over parts and you are missing a good portion of the picture. In a sense, you are losing history. It would be cool to see where technology has lead us and what are friends have accomplished, but it seems to me like it would be more superficial. However, that isn't true for every case, and is probably over-generalized, but I believe that some people would get lost in the glamour, so to speak.
However, if you travel to the past, you would be able to see for yourself the roots of your existence. We know much more about the world now than our ancestors, but certain knowledge and wisdom has been with us for thousands of years. If you are interested, check out a book called "the I Ching," or "The book of Changes." It was written in the 2nd or 3rd millenium BC in China, and has been translated hundreds of times. That, in a sense, could be your time travel to the past.