What do you all do for fun?
Whatever we darned well want to!
That's the great thing about being FI - you can do whatever you want (with the usual caveats, of course).
The subject of "what do you do all day" is a recurring one here and it is all dependent on your own preferences and personality. Some people are content with very little in the way of scheduled, "observable" activities, while others pack their retirement with as many different pursuits as possible. Some don't completely settle into post-work life and go back to work.
As for your comments on travel, I do remember taking a trip on my own once. I couldn't get used to doing it on my own and came back after a couple of days. Nowadays, I think I'd be a lot better at traveling on my own. I've heard some say that they love traveling solo, as they are more open to meeting others and experiencing new things. Others prefer to share their travels with someone they know well. All I'm saying is not to write off solo travel too fast - it may be something you could get used to. Alternatively, perhaps you'll meet someone you can travel with.
I went back to an old hobby after stopping work and achieved some new things with it, starting a blog and getting mentions in a few magazines and a book. It was quite gratifying to receive the acknowledgment, though the best bit was proving to myself that I could do the things I set out to do. My other main pursuit - a very time consuming one - has been committing my entire CD collection (originally numbering about 10,000) to hard drive. For most people this is a simple task, but not for me as I require accurate rips, and scans of every single page in the CD booklet, as well as the jewel case insert, and the CD itself, before I can bring myself to get rid of the CD. Then my cassettes need to be digitized, then the 1/4" reels, and then the broadcast carts. My goal is reduce my collection to the point where it will be easier to move/travel/live in an RV. I figure it will take me a few more years.
When I'm not doing the above, I'm playing with, and doting on my cats. For the most part they like it but I think they are sometimes secretly relieved when I go out so they can get some uninterrupted napping time in!