The few that still fly in the OKC area, fly at Lake Hefner, off of the Britton Rd exit, and just south of the marina. If you want to see kite surfing/boarding, Go north of the Marina on Lake Hefner. Contact Terry Officer at: 405-341-5477
Here's a kite calendar web page that I maintain, that list most all kite events in TX, KS, OK, LA, AR, NM, TX: http://tkogunn1.tripod.com/kitecalender.htm
My contact info is listed on the calendar page.