Another option you might want to consider is to get one of the newer, more forgiving cross style or even road/touring style bikes that can take fat tires: you'll get a more comfortable riding position - particularly if you go for a flat bar handlebar - and big fat tires like Big Apples should offer some good suspension. The gravel you describe does not seem like it requires a lot of suspension.

If you go this route, you might also find some older steel frame, road style bikes that can accept wider tires. Steel is generally a bit more forgiving than aluminum, and if your rides are 20 km or less, you shouldn't need a bike with lots of *new* technology. A reputable LBS that carries restored bikes might be able to provide you with a much better value package than the price of a brand new bike.

I'm with the others who say go one way or the other: either more road, or more mtb. I have an old GT hybrid. It's a decent bike, and useful for all sorts of situations, but not particularly great in any one situation. It sounds like you'll be on pavement or packed trails primarily, and that suggests a more road oriented bike might serve you better most of the time.