-chat about life and the things in it (although I'm often the quiet one...)
-go to inspiring places, which could be anywhere really
-watch Black Books or another good show on the sofa
-eat good food
-play board games
-play music on any number of instruments
-read books aloud, or form a marching band, or go on a silly hat picnic, or...
I often enjoy spending time by myself, it's the best way to relax and recuperate. Being alone in company is also nice, when you do your own stuff and let the other person do theirs. :3