Gunsite's been mentioned. I'd add other options as being:
Bill Jeans and Morrigan Consulting -
www.morrigan-consulting.com ;
Louis Awerbuck & Yavapai Firearms Academy;
Randy Cain & Cumberland Tactics -
www.guntactics.com ;
I've heard FrontSight is good and have friend teaching there. Gabe Suarez
www.thehalogroup.com would be worthwhile as well.