I have a Surly Karate monkey that I have set up as a trail/camping bike but mostly I just ride to work on it. It has as much tire clearance as you'd ever need and one set of front and rear eyelets, which means you can still mount a rack and fenders but it takes some creativity. It's probably heavier than you need for commuting, just like any other bike that accepts 29inch tires.

Since you're in the UK, have you ever heard of Singular Cycles? You should check out their Perigrine (http://www.singularcycles.com/bikes.htm). Yeah, I guess it only takes 2.0 tyre, but otherwise it lookes pretty wicked.

ps. I had my heart set on 26x2.35 Big Apples for a different bike but they didn't fit, so I got 2.0s. They're plenty cushy. I can run them as low as 35-40psi without severe rolling resistance penalty. Usually, I'll pump them higher, but lower pressure sure helps you float over potholes during half-asleep morning commutes.