Crocs again! (and not only because of that picture to the left)
All I ever use when not in my touring shoes (on tour, that is).
Lightweight, indestructible, good in any dodgy showers you may go into, fast-drying, cheap, available in whatever colo(u)r you deem acceptable, unfashionable, bendable/stuffable/easily strapped onto wherever - one of the few 'modern' items I like (although I didn't 'discover' them until they were no longer popular). Could there be any alternative?
I've used mine for plenty of hiking on rocky and hilly terrain, through recently cutover woodland (lots of sticks! careful!), in the shops, to the diners, down the sidewal - er, pavements, in the saloon, in Lake Superior, on the ice, etc. Even biking!
Was looking at a photo of a 1990 tour the other day, and shocked by the ugly new balance sneakers I was carrying at the time.