If no one has suggested yet I would look at a cyclocross model. Think road bike geometry beefed up to go on trails. We're not talking rocky single tracks, we're talking packed gravel, dirt rail trails, that kind of thing. I'm looking into them because I like to do the C&O Canal but also want something that's a bit more of a road bike than a mtb. Like anything you're not really going to know what you like until you get on it and the only way to do that is test riding. Go have fun checking out your local lbs's and trying out some different bikes.