Daughter is 15 now, and in a couple of weeks we'll be off to the Petra Mare hotel in Crete, all-inclusive. They had child price up to age 16 (First Choice) at this hotel, which is unusual for an all-inclusive and because I booked early she got a free child place.
Last year we went to the San Miguel hotel in Ibiza (Thomson), again all-inclusive, and again with child prices up to age 16. The year before that (when she was 13) we went to the Club Sun City in Olu Deniz and again, they were doing child prices up to age 16 and she was lucky enough to get a free child place there too!
If you browse through the brochures and check the small print at the bottom of a hotel's details, it will tell you the child age. You might be surprised to find quite a few more than you think offering HB/AI with child prices up to 14/15 or 16. I think the H.Top Hotels on the Costa Brava do child prices up to 14, and a lot of the "Magic" hotels around the Benidorm area do it too