Games or toys?
I have also been experimenting with getting my games out with Alex and Cori. For being 4.5 and 3, they do a great job of being kind to the games. Yesterday we got out National Geographic Global Pursuit and Carcassonne to see how they would do. They did great at manipulating the tiles and taking turns drawing and placing cards on the Carcassonne map. Alex directed the traffic with Global Pursuit, quickly deciding that we should sort the point chips, then roll the giant 12-sided die and count out a single color of chips for the total shown.
Today I got out Ursuppe and Agricola for them. Ursuppe doesn't have much in the way of play-inducing parts, as the food cubes are pretty generic and the amoebas are functional game pieces but not good for imaginative play. Agricola kept the girls attention a lot longer because the animeeples are great for sorting and stacking. Cori said, "These sticks are a bed for my sheep."
Cori's definitely got a shorter attention span than Alex, but both of them can take turns well. Overall, these are a hit. I'm more wary of allowing them to handle cards, since the likelihood of the cards getting folded/spindled/mutilated is pretty high. Lee and I have also talked with the girls about the concept of good stewardship... there's little incentive for us to get them cool toys if the girls carelessly destroy them.