I just thought i'd throw in my opinion here. i think you're on the right path with the MTB. Modern road bikes for the most part just aren't versatile enough for utilitarian needs. You can always turn the MTB into a pretty good roadbike, but it's hard to turn the roadbike into a off-road machine.

So here's my thoughts. first have you considered a rigid MTB. You know, one without any suspension. I know their getting hard to find, as manufacturers tend to put suspension forks on even low-priced bikes. However for what you have to spend you could probably get better components if you went without a suspension fork. I doesn't sound like you're going to do a lot of off-roading so the suspension fork is probably not needed and might even be a hinderence on the road.

Secondly, if you can wait until the end of summer you'll probably be able to get a better deal at the bike shop. Okay, and you can all hang me if you want, but there are some good deals on bikes on the internet. Places like supergo.com and jensonusa.com have excellent deals on complete bikes and are quite reputable. if you know what you're looking for and know the size you need you shouldn't have a problem buying over the web. you'll have to pay shipping but you won't have to pay sales tax if the company is out of your state. It's just an idea. Of course, if you have a good LBS it's your duty to support it. The shops near me are pathetic. So i have no remorse in buying off the web.