My opinion closely follows what seeker333 posted.
I think the utilitarian version of "classic" touring wheels use some combination of the following components: Shimano LX or XT 36 spoke hubs, DT or Wheelsmith spokes and Alex, Mavic, or Velocity rims. There are folks that talk about Phil Wood and White Industry hubs, but those are at the high end of the spectrum. I'm sure that there are several other good combinations out there, but these are the components that seem to come up the most. They are also the components most manufacturers use as OE on their touring bikes.
I have 3 sets of wheels made by Universal Cycles in Portland. They were all built for loaded touring. Two pairs of those wheels have seen some pretty hard use. The hubs are the only differences. We used XT, Ultegra, and 105- 36 spoke hubs. Two of the bikes have 130 mm rear dropouts.
The pair on my LHT are: 36 spoke XT hubs, 700c Velocity Dyad rims, Wheelsmith DB spokes, with brass nipples. The reason I went with the Dyads rather than Mavic rims was the weight. The Mavic 719, 319 and 119 rims are great rims, but a little on the heavier side. We also have a couple of bikes with the the original equipment Mavic 119 rims, and LX hubs that have held up very well. I put them on the LHT when I first buit it up, and it is just turning over 7,000 miles. The majority of that is loaded touring. No problems at all. My wife has the set with the Ultegra hubs on her bike, and has slightly more miles on her wheels. She is pretty light and rides a 49 cm frame. It is no surprise that her wheels have also held up very well. On the firsts tour after we put on those wheels, part of our route took us over 400+ miles of dirt and unsurfaced roads and trails, and 500+ miles of cobble stone/paver block roads and trails. I was really glad we decided to go with the new wheels.
Universal Cycles allow you to choose your components, building a custom wheel. Their prices are very reasonable, often less than the cost of tthe individual componets if purchased separately. They also provide exceptional cotomer service and fast delivery.
http://www.universalcycles.com/wheelkit.php