Thanks for all the great advice. My DS does have fine motor difficulties, so we may hold off for this year with the K'Nex. I think he (and my DD10) would LOVE the Lego robotics kits, but I'm not ready to pay the $300 unless I know that it will get a lot of use. It seems that either Magnatiles of the Magformers may be a bigger hit for him. Right now leaning toward the Magformers because he could actually pick them up and create more complex 3-D structures because they have stronger magnets. He doesn't build mazes or anything with the Magnatiles, so I don't think it would be a disadvantage for him that they aren't solid tiles.
