Yeah man, Woodstock for sure. And I'd love to experience some of the famous people that were around then and didn't make it to today. JFK comes to mind. Also just to not be bombarded with wifi signals all the time. I think our brains were clearer and there was less 'noise' in our thoughts back then. I used to really enjoy taking a few days off out at my family's cabin, before they sold it 5 years ago. Even before you arrived, you could feel the interference fading away. I'm pretty sure it wasn't just the fresh mountain air :)
If only we could go back, but know what we know now.