I picked an hour but that is pushing it. My winter commute is about 45 minutes which is longer than I like. The rest of the year it's 30 or less but on the way home I'll take a longer route a couple of times a week. I don't mind a longer ride on most days but it's more time than I want to commit to getting to and from work.

On a good day I can get to work in 25 minutes, so about 50 minutes on the bike per day with the option to go longer. I think that's about perfect. It's long enough that I feel like I've earned my snickers bar and short enough that I feel I'm not giving up any time over not choosing to drive.