I suggest to just get Bionicles for sub-12yo age group. I'm not sure if they can appreciate the build engineering and little details that most of the themed sets (outside of City sets) out now. Definately just get them Bionicles, especially if they are rough with their toys.

piratescratch: The Coast Guard Platform is at Kmart and definately a good time to pick it up now while the 15% off sale is on.