Liesl is 12mths old, we've been taking her to a local business called Rover Oaks sporadically since she was 5 months. They are basically the same type of set up as CBW--screen the dog for half a day to make sure of its temperament, then let a pack of about 20 dogs play together on a spacious playground, with climbing and agility equipment, and several young men supervising and assisting the play, throwing balls, etc.
She has gotten along well with the other dogs, and based on our short observations all the other dogs have done well with each other. She has enjoyed these visits and gotten lots of exercise, come home pooped (fell asleep in the car on the early visits!).
Maybe I just haven't had a bad experience "yet", but I give these places a thumbs up. She is very well socialized with dogs, and wags her tail and enthusiastically greets all the dogs we see on our walks, even the foul-tempered little ones. By nature she is weak-nerved and a little timid until she feels comfortable, then turns into Ms. Personality. I think her experiences at Rover Oaks have helped build her confidence with dogs and people (but we also work heavily on socialization due to her weak nerves).
So, my two cents is that if you are comfortable with the setup and your dog likes it, go for it. If there is a bad experience, then you decide whether to continue there or not.
Liesl, b. 1/1/11