Andean Face Local Ecuador Guide Company
International Mountain Guides
Mountain Madness Guide Company
Rainier Mountaineering Inc. Expeditions
San Juan Mountain Guides
Alaska Mountaineering School
I have used each of these guide companies at one time or another, and can vouch for their excellent service.
I have been active more or less on each of these. You can find route info, friends to climb with, and gear to buy and sell on most of these if you dig in the forums.