If you truly have *no* interest in technical mountain biking -- extremely rocky, rooty, steep terrain -- then you probably don't really need a mountain bike, and you may not want one. It's true that with slick tires in place of the knobbies, it will roll more smoothly on paved or relatively smooth dirt trails, but it's gonna be almighty heavy compared to a hybrid, and probably even compared to a "comfort" bike.

I have routinely ridden my cyclocross bike, with 32c tires, on dirt trails like the C&O and the NCR with no trouble (and much enjoyment.) (To most cycling newbies, a 'cross bike looks a lot like a "road" bike -- same sort of "racy"-looking frame, and those dropped/curved handlebars.) And that's a type of bike that is, in general, a bit less stable and "comfy" than a hybrid. For the type of riding you mostly want to do, I would think you should be perfectly fine on a hybrid.