What type of harness do you use?  

I personally use a Petzl climbing harness, and most people I climb with use one as well. Other then that I also recommend Black Diamond products, the company was started by a long time Yosemite big wall climber.

As far as choosing a harness goes, I'd stick with the name brands - your life depends on it after all. Try to find a harness that is comfortable and suited to your body type, it can be a real pain if your harness doesn't fit properly, especially at hanging belays.

Some people also like to be able to easily tighten and loosen their harness straps. Personally, I don't mind a harness being hard to tighten, as long as it's not impossible. In fact I actually prefer it as there's less chance of it loosening while I'm climbing.

Hope that helps.

I use a Black Diamond, hasnt let me down yet =P and it ive had it for quite some time.