No need for the 29er label...it is just a marketing term. Consider the A719 as already suggested - an excellent rim. Others are the Velocity Chukker (very heavy though) and the DTSwiss TT series.
Deore XT hubs as suggested a good budget suggestion...Phil Woods are nice but ain't cheap.
Double-butted 2.0/1.8/2.0 DT will suffice - put the parts in the hand of a very good wheel builder - you'll be all set.
Avoiding a too-knobby tire makes the tire a little more efficient on asphalt - while still responding well off-road.
Pretty much echoing Jeff and FB here...
=8-)
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5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:
Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life