You could try the Canary Islands, which is priced as out-of-season in the summer, although it is still lovely and hot. Princesa Yaiza hotel has rooms with a mini kitchen, so you can self-cater, as well as a kids club and teens club to suit both your kids.
See
http://www.totstoo.com/hotel_princesa-yaiza-suite-hotel
Another good choice would be Martinhal in Portugal, where you can have the freedom of self catering in a villa, but enjoy all the facilities of the hotel. There's a kid club, and all the teens meet up at the Blue Room, with table football and video games.
See
http://www.totstoo.com/hotel_martinhal
Hope you find somewhere that you like!