This is not exactly a "gifted child" question, but I am curious what type of building block sets your gifted kids have enjoyed playing with. I have a 2.5 year old who loves to build, and she could stand to move beyond the Duplos. I was considering getting her a set of unit blocks, but the good sets are rather pricey. I didn't want to make the investment without asking parents of older kids first whether their children actually play with them in the long run. It seems like most of the older children I know play with legos.There is something more charming about the wooden unit blocks to me compared to the plastic legos, but mainly I am curious about which type of building set is the best tool for fostering spatial creativity. So, what have your imaginative little architects enjoyed building with? Any suggestions for specific brands?