Have you tried looking for just doggie socials? In my area there are a great many training places that have socials. They are usually about $5 - $7 per visit. Since you seem to be doing well with the training and are only concerned with keeping him socialized, you might want to check it out. Plus you can work on obedience with distractions yourself while you are there.

I don't have a big objection to using choke collars for training, I just think there are so many better ways to train using treats, clickers, and positive reinforcement.