There are allot of nice gravel/all around bikes / CX in the 2-3k range. The problem is that most shops won't stock them for test rides. I think Salsa still makes the war bird.
If you're going to be on mixed trails, I'd say pony up for carbon or steel to take some of that high frequency gitter away. The tires and rims can only do so much, if you do go alum, you might have to resort to carbon bars and seat post to do the same thing. More for endurance comfort after a couple hours on the bike, it makes a difference.
Niner BSB Ultegra Jenson Bike > Bikes > Cyclocross & Gravel Bikes | Jenson USA
Niner RLT 9 Steel 2 Star Apex Bike > Bikes > Cyclocross & Gravel Bikes | Jenson USA