I suggest you take a look at the Marin dualies, as the East Peak ($1,430; www.marinbikes.com) has the same monocoque frame and rear shock design as my much pricier Mount Vision Pro, and it's a well-regarded design that is light, efficient, and exhibits almost no bobbing on climbs. The East Peak also has the molto desirable Fox Float R rear shock, plus a decent component package, with Shimano drivetrain and Hayes hydraulic brakes, and a Rock Shox front fork.
Giant's Trance 3 ($1,700; www.giant-bicycle.com) has a very similar component package. Its rear suspensionthe key element to a dualieworks on a principle similar to the Marin, creating a floating or "virtual" pivot point that helps reduce bob and actually pulls the wheel over obstacles. Giant, however, goes about it in a different way. On the Marin the shock is mounted on the top tube, and the pivoting frame pushes up and into it. On the Giant, the shock (a Fox Float R as well) is mounted near the bottom of the triangle, and the pivot pushes down onto it. Both makes, of course, claim their design is the best ever.
Specialized's Enduro ($2,200; www.specialized.com) splits the difference, with the rear shock mounted pretty much horizontally. It has a somewhat better component group than the Marin or Giant, thus the higher price. Much of that goes into the excellent Marzocchi front fork.
I think the solution is to ride some of these bikes. They'll all work well, so it's a matter of what fits best and seems to work with your riding style. A good shop should let you take one for a spin, if not to hammer it on a trail, then to get a sense of its feel. Find a steep hill near the shop and do some sitting climbs, which will tell you a lot about how the bike performs.
Pick up a copy of the April issue of Outside for 2006's best new bikes.