I love my bus pass and it's one of the big reasons I bought a folding bike. Fold the bike and onto the bus I go!
When I first got my bus pass, 15 years ago, I travelled to a course in Oxford with it. Took me three days to get there, with 2 nights b&b on the way, and I had a great time. I did come back by train, though - it cost me less than another 2 nights b&b would've!
A little judicious studying of the regulations, timetables and T & Cs, and you might well be surprised where you can go even if it's not with your bike. There are some simply stunning bus routes which you could pay a high price to take a coach tour along, and which you simply can't appreciate from the generally-low viewpoint of a car even if you're a passenger.