I commute on a Motobecane Phantom Cross and love it. I recently switched out my stock 35mm knobbies with some 35mm slick city tires. I can tell a big difference just between the knobbies and the slicks. I haven't thought of going much smaller then 35's as part of my commute is on a road that is just loaded with crap. Granted my commute is only 5 miles one way, not your 36 miles so over the longhaul I might want smaller, higher psi tires.

I have a road bike as well which I love to ride on the weekends and in groups, but in terms of a "go anywhere" bike, I love my cross. It gives you the road bike setup with the option to go anywhere, crushed gravel, dirt, grass etc. I mounted a Axiom Streamliner rack on the back along with Axiom panniers. Last year my wife and I went on a week long camping bike trip, I used my road bike and mounted the same rack and panniers. It worked fine, but the bike was a bit squirly with all that weight in back. This year I plan on using my cross bike for the same trip.