when we first got legos for the kids, my husband and I bought the blocks that we remembered growing up. we had both played with legos alot growing up, I had built houses for the little fisher price people I played with constantly and my husband had built rocket and planes that he found in pictures in their set of encyclopias. so we both had our little preconceived idea of how to best play with them and we were resistent to the sets. the boys had different ideas though and they really enjoy playing with them in all different ways. they love the sets but put them together once,play with them awhile then all the pieces join the collective. I see pieces i recognize in all kinds of new creations. they use the movable pieces to put doors, guns etc on new creations that wouldnt have the option of if they had never had the sets. i have also been looking at the motors, but my kids do seem to do better with ones that have projects and then they go from there on their own. i have trouble finding which ones include motors.
one thing my kids have really enjoyed lately is finding the little videos on youtube about how to build mario, bowser, link etc... We have all these little guys all over the house right now. They then change them to fit their taste.