I think you are on the right path, but I'd strongly suggest looking for a year or two old Specialized Sirrus or Trek Triton (or somesuch). Many people buy bicycles like they buy treadmills, all the good intentions in the world, but many spend their lives sitting in the garage unused. So rather than paying for a "new" big-box store bike (which will be pretty budget and certainly poorly set-up), you can get a much higher-quality bike for about the same price. Plus you'll end up with something that will last longer and hold up better.

My other morsel of advice would be to avoid the MTB thing. Fat tires and flat bars really kinda suck for road riding. Drop bars, while they may look funny, really are easier on the wrists and will help make your commute/travel time more comfortable.

dp