Back in February I moved and changed jobs. My bike commute went from 6 to 12 miles one way. In addition, I went from having to be in by 8:30/9 to no later than 8:00, so I have to leave about an hour earlier than I used to.
My commute is mostly rural, with low traffic, no stop lights and only a couple of busy road crossings. So far, I'm loving it. I often finding myself leaving even earlier so I can fit some extra miles in on the way to work and/or doing a some extra on the way home.
There are plans for my office to eventually move, putting me closer to 18 miles one way. But that may not be for a while.