I started my son in Tae Kwon Do....and I loved it and so did he, but our studio closed their location close to us and changed the rules on contracts that left a bad taste in my mouth. (They wanted our money, but didn't really care if my son was there or not and there was no personal care about the students...I saw we were a number to them).
I went studio hunting...we went from studio to studio and did trial classes...usually after one class I knew that it wasn't a good fit...or once I reviewed the long term contracts they wanted us to sign (three to five year unbreakable contracts unless we moved). Argh!!
Then I was driving by a strip center and saw a sign Korean Martial Arts...so I stopped in and found out it was a brand new studio. They don't teach Tae Kwon Do...but Mu Sool Won (actually Kuk Sool Won, but our association had a split and changed the name to Mu Sool Won, meaning family martial arts) a sister Korean martial art to TKD.
I couldn't be happier...the owner/main instructor really cares about each student...we are a family center in fact whole families take together...we are all one big family supporting each other in healthy living and learning. I don't study martial arts, but attend the evening Tabata classes that are offered for body conditioning for adults.
Make sure the studio only promotes students on merit and not just you get a new belt every so many weeks because you pay for it...make sure the student shave to learn the skills. (Some studios promote students as long as the parent keep paying).
Go visit each studio...I think the owner and morals/vision of each studio is more important than the "style" of martial art. So shop around and look for a good fit for your boys.