Before buying any bike, go to several bike shops and test ride all the bikes you can, so you will know what size feels best.

I agree that you should stay away from mountain bikes. They're unsuitable for the kind of riding you'll be doing.

In my opinion, a road or touring bike with clearance for larger tires (28+) and eyelets for fenders and racks is the way to go. Trek, Miyata, Bridgestone, Bianchi, etc., are good brands to look for.

You might try placing a want ad on Craigslist.