Most spots in Greece are either flat or choppy, no "real" waves there. But the wind is super reliable and strong in summer.
To combine family and kiting, I can recommend the island of Naxos. The spot (Mikri Vigla) is relatively choppy, but beautiful scenery, you can rent all kinds of acomodation (good infrastructure) on/ close to the spot and there is a stunning, wind protected beach on the leeward side of the Mikri Vigla Peninsula within walking distance of the spot and most acomodations for the family.
The island is also very nice, plenty of other activities that you can do with the family. And if you are bored kiting in Naxos, Paros is just a 30min ferry ride away, easy for a day trip.
Wind: Make sure you take a 7 and a 9m, those are the most used kite there in July/ August..
Greece is great