I've been caffeine free now for about five days. I had gone caffeine free for a week or so a few months back. Both times, I have experienced much better sleep (especially being able to far a sleep much more quickly), greater, much more even energy throughout the day, and improved mood.
Most Americans consume lots of coffee. I think many folks would benefit a lot from cutting it out for a while.
I am a lover of Chinese tea, and I cherish coffee-fueled philosophical conversations with good friends. After a month or so I'm going to try reintroducing it and see how I react. But it would only ever be a couple of times a week. I will compensate by drinking only really good tea.