I bike commuted all the way through college, but I only lived 2-3 miles off campus. A rear rack with panniers or large seatbag (like Carradice) is almost a necessity for the distance you are considering. I mostly used a backpack in college, which is fine for shorter distances, but I wouldn't want to ride 17 miles each way wearing pack. A road or cross bike would also be preferable, although a mtn bike with slicks would be OK. I agree with others about a backup bike if you can afford it. If not a spare rear wheel will cover 90% of my backup needs. Make sure you get some good front and rear lights as you inevitably will end up riding in the dark from time to time.