This is a tough question to answer. I've hunted elk for 11 years and have been on two fully-guided hunts. I wasn't real happy with either one of them, and now prefer to hunt on my own, or with trusted friends.
One guided hunt was marred by guides drinking heavily, and the other by a surly, impolite outfitter who had a talent for rubbing everyone the wrong way.
If I had to consider another guided hunt, I'd talk to the outfitter a LOT about the details of the hunt before committing. References are good to check, but they'll usually only give you the names of favorable clients. Repeat customers would be the best to talk to. Also check membership in outfitter associations, and see if past clients have filed complaints.
I would NOT pay much attention to magazine advertising. I've heard of some outfitters who advertise heavily to keep getting a new client base, because they don't get repeat business.
For elk, I lean toward outfitters who are involved in the RMEF(Rocky Mountain Elk Foundation). Shysters and fast buck artists usually don't donate to good causes. If you can make it to the sport shows, it's good to meet an outfitter and get an idea of their personality. Beware the man who promises too much.
I guess I'm really saying that you have to hunt for a good outfitter, just like you hunt for game.
Good Shooting, CoyDog