It is really depending on who you get at Petsmart. Charlie's was ok, but I don't like the other big guy.
Now we have a trainer who comes to our house, he's fine, but the work is really ours but charging us a lot. The first lesson he just talked and talked, showed us a few tricks in front of the house how to heel the dog. We haven't had the second lesson yet, he said to call when Charlie is ready?! /forums/images/%%GRAEMLIN_URL%%/confused.gif Or we think he is ready...the heeling part has to be mastered first. Also, I need to get my control back. He was kinda taking over me! Getting better.
I would first go in the Petsmart store and talk to the trainer first. Find out their training methods. Tell them what you expect from your dog. Then go by your feeling.
We did our classes at Petsmart but the trainer was a friend of mine. I would go to the store and watch some of the trainers work and find one that you feel comfortable with. They all follow the same curriculum but have different styles of interacting with people and dogs. I think the Petsmart classes are probably fine unless you are having some unusual behavior problems or want to go on to compete in agility or obedience.