Although I'd love to travel to the future where quick space travel has been discovered and developed so that I could visit other worlds I don't trust our species to get there at this point in time. As a result I'd want to go back in time.
I know it would be risky and most likely fatal due to different pathogens and other environmental dangers but I would love to go back to witness the dinosaurs. I'd also like to visit certain areas, Yosemite, the Grand Canyon, Sequoia National Park, the San Francisco Bay area, etc... after they had formed but before they were inhabited or developed. And then more recently I'd want to go back in time to see the bands I love from the past perform at different stages of their careers.