I recommend Infant Swimming Resource (ISR)- you can find them at infantswim.com. The teacher closest to you is Sheri Philips- she's great!
I would definitely stay away from Mr. "D"- we tried him last year (switched from Sheri only because Mr. D was closer to us and a man- my son prefers men) and he was horrible. The lessons are mostly the same as ISR (he used to be with ISR, but I think he got kicked out) but he pushes the kids too much. My son (at 18 months old) didn't get a chance to take a breath for 10 mins and after the lesson nearly passed out- his eyes were rolling back in his head! Mr. D is dangerous and I would recommend that no one go to him. I sent him an e-mail telling him all this and saying that we would not come back and he didn't even have the consideration of e-mailing me back. We returned to Sheri and were very happy that we did. She understands that every child is different and needs to be handled differently.