I built disc specific wheels for my 29er mountain bike; I used Mavic's TN719 Disc rims, which are available in 36 hole. They're a high quality double eyeletted rim, welded seam, very robust, made for the rough and tumble world of mountain biking. The rims have a 622mm bead seat diameter, which of course is the same bead seat diameter as a 700c road wheel. The thought has occurred to me that if I ever have a disc brake equipped touring bike, these would be a good rim choice. I've used mountain bike tires as wide 2.25" on these rims, and I'd feel comfortable putting something like a 700 x 28c road tire on there as well. These rims don't have a braking surface that's suitable for rim brakes, so they're considered disc specific rims.
As for hubs, I've always had good luck with Shimano XT, both on mountain bikes and touring bikes. Not crazy expensive, good quality, and serviceable, which I think makes sense for touring. Do keep in mind that these are mountain bike hubs, so the rear hub has 135mm spacing. Also keep in mind that the hubs you get need to be disc compatible, and there are two common mounting systems for mounting the brake rotors to the hubs: 6-bolt (most common, pretty much all brake brands except Shimano), and Shimano's centerlock, which uses a splined interface. FWIW, Shimano's XT M756 rear hub uses the 6 bolt rotor mount, and the XT M775 uses the centerlock. Both are available in 36 hole. Since I used Avid disc brakes on my bike, I used the XT M756 hub so that I could use the Avid 6 bolt rotors.
I've used Wheelsmith double butted spokes (2.0/1.7/2.0) on most of my wheelbuilds lately, including the mountain bike wheelset I'm talking about. I also like DT double butted (2.0/1.8/2.0).
Here are pics of my 36-spoke Mavic TN719 Disc rim/Shimano XT hub wheels on my mountain bike. The bike is a Jamis Dragon 29, with Avid BB7 disc brakes. The tires on this bike are WTB Wolverines in 29 x 2.2," which I run tubeless with Stan's rim strips and sealant. I think the wheels on this bike would make very nice touring wheels on a disc brake equipped touring bike that's designed for 135mm rear hub spacing.
