I'll admit that I wanted to use Chris King hubs on my latest personal set of wheels, but my budget led me down a different path. I honestly haven't had problems with any of the XT, Ultegra or Dura-ace hubs that I own. All Shimano are cup/cone.

I don't think anyone could give any better advice than scruggle did. New wheels and tires appropriate for your riding circumstances are great early upgrades. At the shop, I steer people towards improving the contact points, grips, saddle, although both are highly subjective. Durability, being comfortable and enjoying the ride makes more sense to me than shaving 20 grams here and there, unless you've been losing Cat 1/pro races by fractions of seconds.

At your size strong double wall rims on a good hub make a lot of sense if you don't already have them. Are you happy with your pedals and shoes? There's another contact point to think about.