I think generally, something like the cross check is a good choice. The tire clearance is pretty good, and you have the option of gears. If you really want to focus on mountain riding more, i would proabably look at something like a karate monkey instead, as it could be set up as a very capable mountain bike, or a heavy-ish cross or road bike.

Personally, as I spend more time on road and singletrack, a cross frame seems like a good choice. If you can afford it, I would look at a titanium frame. I'm eyeing up Spicer (www.spicercycles.com), as they make a pretty nice TI cross frame, which i think they could put an EBB in and still come in under $1000. Of course, that's a lot more than a cross check, but is a good deal for TI.

Or you could get a burro ... http://burro-zvobikes.com/index.html