Co-Motion are great bikes but logistically may be difficult (Oregon), and they are pricey ($3K or so?).
I second the vote for a Surly Long Haul Trucker, if you can get one built up by a good LBS.
Another excellent rig for you would be a Cannondale T2000, which has a very strong frame for heavier riders. The T2000 also comes with excellent wheels and components, and will handle large tires.
The LHT and T2000 are both outstanding tour-ready rigs, reasonably priced and warrant a serious look, even if you have to travel some distance to try one out. I would not buy any bike without a test ride and proper fit.