I'd go XT rear hub (135), whatever front hub (doesnt have to match), Mavic or Velocity rims, and either DT or Wheelsmith 14/15ga butted spokes, and brass nips.

If you want to save some weight, make the front 32 spokes. 32 is adequate for loaded touring for the front, and plenty strong for your needs. This is due to fact that an unloaded bike has a typical weight distribution of 40/60 f:r at best. For a loaded bike more like 20/80 f:r or worse. Rear wheel is stressed, front hardly loaded at all.

I prefer WS to DT spokes, as their butted spokes are just as good and a little lighter since they're 2.0/1.7mm vs DTs 2.0/1.8mm. Butted spokes usually cost a lot more than straight gauge spokes, probably add 30-40 bucks to cost of wheelset. So if cost is a concern, stick with 14ga SG spokes, doesnt add that much weight. Neither does 4 more spokes on front (32v36). Just saying you dont need them.

http://www.wheelsmith.com/spokes_db14.html

The 135mm rear Shim hub will build into a slightly less dished wheel than a 130 Shim hub, with the 135 r wheel having slightly greatly longevity. If you want to improve this some, get a Velocity asymmetric-drilled rim and build rear wheel with it. Vel makes 2-3 of these rims in 700 IIRC. Synergy is one I have used for years:

http://www.velocityusa.com/default.asp?contentID=591

Most wheels are built 3X, not 4X.