Get a 29er mountain bike that is an upgrade from what you have. This fall I discovered just how excellent it can be on the road with the correct tires. The next bike I get will be a hard tail 29 rigged for touring or day rides and set up with drop bars. They really are the best platform for an all-rounder bike.
Check out habcycles.com. Picked up a road frame from them this past spring and absolutely love it. Will be getting another one in the above described model sometime in the near future.