In touring, people usually talk about Velocity Dyad or Sun Rhyno Lite rims. I know the Velocity Deep V might be used for 200+ lbs riders on road bikes but the Sun CR18 according to Harriscyclery cannot take more than 200 lbs.

36 hole rims is usually the standard although some say they can get by with 32 spokes.

Shimano Deore LX hubs are usually preferred although if your dropout is 135 or 132.5mm. Or, in 130mm, a Shimano 105 hub. [I wouldn't mind going down to Shimano Deore (135mm) or Tiagra (130mm).]

Spokes often used: DT Swiss, Sapim, Wheelsmith (not Wheelmaster).

Sites for calculating spoke length:
http://leonard.io/edd/
http://wheelbuilder.jmoore.me
http://www.wheelpro.co.uk/spokecalc/