Why dont you just get the brochures pick some places out where you want to go and then book them late.
I used to book in advance with free child place but the last few years I have booked between 8 weeks to 4 weeks in advance as it is always cheaper.
I have a friend who is a travel agent and she told me that there is no such thing as a free child price, she said this only exists if the parents are paying too much for the Adult price or another person who booked paid a lot more.
We generally pay around 1200 pounds for two rooms (five of us) for two weeks at good four star or min three star+ accomodation in the school holidays for greece,although you can go even cheaper in Turkey, Ibiza and other places as I check them all before we book.
We never ever pay under occupancy supplements and pay half the brochure prices.
There are more self catering deals on last minute sales as they sell these to fill left over seats on the plane quickly.
All inclusives and Half Boards do go down too but not as much as sc.