I guess it's not a big surprise that most people like their person commute distance - it's why they are bike commuters! Mine is 40 miles RT. I think it is ideal. It takes me 1:15-1:30 to get to work, then I repeat that to get home. This keeps me in shape to go touring without "training" for it. And I like being able to take weekend camping trips up to the mountains and feel strong rather than like I'm pushing myself close to my limits.