I'd say to stay with the open patterns like Natural Gear, Outfitter and Predator mentioned earlier. Also, look for the ones with the lighter background colors. In my opinion, a lot of the more popular camo patterns are too dark for western hunting unless you hunt primarily in the dark timber. They work fine when you're in a tree stand somewhere back east because your background is dark, but in sage, you need a light base color.
Others to consider might be Cabela's new Seclusion 3d open country, King's desert shadow, prairie ghost, and faded sage. The problem I find with some of the more specialized western camo patterns is that they are offered mostly in cotton materials, which I wouldn't choose to wear in the mountains.