I recently joined this group and fly with them. They have a variety of kites that you and your son can try out.
this is the facebook page.
https://www.facebook.com/groups/emeraldcoastkiteflyingclub/
here is the web page
http://www.eckfc.net/index.html
We fly SLK's, dual line, and quads kites.
My 9 year old started flying dual lines, now he has a quad and flys it better than i do mine.
John