I can vouch for the Trek 7.3 Disc. I have the 2010 version (Trek Valencia), and my wife has the 2011 version. Very nice bike. Comes with 28/38/48 gearing, so somewhere in between MTB and road bike. The stock tires are 32 mm. It's got full eyelets for a rack and mudguard.

We regularly tour on them, taking in road as well as towpath and disused railway. I think it would be an excellent commuter.