It's tempting to simply go back to 1970 America and just enjoy the next 30 years in a less modernized world that was absolutely the best of times to be alive (no cellphones, no internet, people were cool, movies were good, music was good, etc). I'd go see all the GOAT bands live in concert from the 70's, 80's and 90's, chill somewhere in NY or Cali and "people-watch" all day at bars, clubs, city areas, beaches, skate parks, etc.
I can't imagine going back any farther than that. Too much racism, wars, etc. Plus, the lack of air conditioning and other stuff we take for granted in the modern age would make it kind of miserable. Imagine going back to witness Johann Sebastian Bach live in concert, but shortly after you realize there is no legitimate public toilet or bathroom lol. Same thing with going back to Renaissance era Italy, or even what we call Ancient Egypt. Beyond that? Seeing dinosaurs totally peaks my interest. I could probably survive a few minutes in "Jurassic World" before noping the fk out of there lol. In all of those situations I'd have to have the option to time travel back to the modern realm.
The future seems kind of bleak right now, and I don't have enough faith in humanity to fast forward 1000 years from now (3020). It could be like Idiocracy, and the everyone is just dumber and more diseased than they are now. Or it could be like Star Trek, and everything is extremely advanced and clean. Either way, I probably wouldn't be able to comprehend the amount of progress (or de-evolution) that has happened since the present.