If your use is 95% commuting on street, I'd go with a hybrid bike with 29" (700C) wheels. You're likely going to want something with either a very short travel suspension fork, or a rigid fork, likely with a frame that's similar to a basic hard-tail MTB frame.
Maybe more basic than this, but something like this:
http://www.giant-bicycles.com/en-us/...0/14821/66246/
Good to see you looking at bikes after your accident Steve.
To add to Olivia's note on pace:
On an MTB or MTB-based hybrid, expect somewhere around 10-12 mph for an average rider, 15 if you're really trucking.
On a roadie, or road-based hybrid, 15-16 mph is easy without pushing too hard, 19-22 if you're in shape and trucking along at race pace. If you're worried about pace and commute time, do a few dry runs and see how it goes. 10 miles is right on the edge of what I'd attempt without getting sweaty. Take it slow and you should be just fine.
Like olivia said, many places to get good prices on used bikes. Many options out there. All about finding the bike for you and your riding needs.