I would definitely go back to my freshman year in college... or maybe middle school. These were such formative years of my life - I'd love to see them again through my current eyes and with my current experience.
If I could step into a book, I think I'd be really tempted to step into the world created in "Snow Crash" where everything is run by franchises like Mr. Lee's Greater Hong Kong and there are some incredibly cool gadgets out there that people play with, like skateboards with smart wheels that detect changes in the surface you are skating on and adjust to them.
Then again, conditions for a lot of people seemed to be pretty terrible, so I am not totally sure I would do it.
For time travel, I'd be hesitant to go back too far in the past since everyone would have terrible diseases that would probably kill me really fast since I have no immunity. Maybe I would go fifty or one hundred years into the future, see if we kill more or less for oil then than we do now.
Also in favor of the second part, the environment of Jane Austen's novels, especially Pride and Prejudice would be delightful: travel across the English countyside by horse and carriage, social engagments, witty remarks, appreciation for the beauty of the English language. The spirited personality of Elizabeth Bennett and her family make them characters with whom one would enjoy association. Mr. Bennett, the medium for Austen's ironic wit, is "so odd a mixture of quick parts, sarcastic, humor, reserve, and caprice" that he alone would be entertaining.
There are so many places I would like to go and people I would like to meet so this is a bit hard to just pick a couple.
I would like to go to England during the 1500's. I would like to meet King Henry VIII because I think he is very interesting. So much was going on in Europe during that time period. I would also like to go back to when Jesus Christ lived. Societies were built upon Christianity and I would like to meet Jesus himself. The questions I would ask! It would also be great to go back to when the dinosaurs were here. That would be amazing to see.
I like the second question a bit more. I would say that being able to be around Saleem Sinai from Salman Rushdie's "Midnight's Children." Being able to pal around with Saleem during the moment of Indian independence and the Partition that followed would be both intense and exhilarating. Given his constant battles with his nemesis Shiva, he might need a friend. I think that he is highly unique and very distinctive in a time period that is also intensely different from many others. To be present in the nation at the end of British Rule and the start of Indian autonomy and the division that followed is a moment in time. As the Indian population is experiencing a youth resurgence, this memory is becoming a rapidly forgotten one, making an association with Saleem all the more relevant and poignant.
I've thought about this before, actually, and I would go back into the early 1800s American West. I've always wanted to see the places I've traveled and lived now back when they were virgin territory, with old growth trees, full forests of Redwoods, wild rivers and unspoiled beaches. I think seeing the Columbia River and Celilo Falls south of Washington in it's natural state, fast flowing and filled to the brim with salmon, just like what Lewis and Clark saw, would be incredible.
Now, of course I'm assuming I could still run to the corner grocery, or that my hunter-gatherer skills would be up to par (don't count on it) or that the Native tribes of the region would even let me stay, but it's an interesting idea to think about.
I guess everyone has considered this possibility. My choices change with the passing years. Since I've been watching The Tudors (the Showtime series about King Henry VIII) lately, I'd probably like to visit 16th century England and witness some of the events of the period. I'd prefer to be a wealthy aristocrat, however, since the commoners of the period had it pretty rough. I would hope to take back a few modern medicinal necessities and cure Henry's ailing leg and hopefully lend a hand to help contain the Black Plague that ravaged both rich and poor.
If I could time travel, I would go to the time of one of the great floods that came out of glacial Lake Missoula in Montana and rushed across the part of Washington where I live. At least, I would do this if I could bring a helicopter with me or at least be up on some safe place.
It is said that huge amounts of water were released in these floods. They carved out the landscape around here, making huge valleys called coulees. Then they ran down the Columbia River to the Pacific. It must have been an amazing sight to see all that water rushing down in these huge walls...
If I were to travel through time, I would most definitely go to Bethlehem to witness Christ's birth. I would want to observe his life on earth and experience first hand all that is assumed about his life. I would also like to visit England during the time of Chaucer. I love his works and would like to experience this time period to gain a better perspective of how people lived.