I can only speak of the classes around here, but they are not recommended. Petsmart are dog supply stores, not obedience professionals. I would suggest you look in the yellow pages around you and see what else you can find. The facility I go to in Kitchener comes with University educated obedience trainers.
I personally would keep searching.... Go to each place and get a feel for things. Definately ask what their preferred methods of training is, as some use aggressive methods, where others (like mine) use only positive reinforcement training.
Heather and her 3 Golden Girls.