I'm not quite sure what you're looking for here but since you're dealing with small children, I wouldn't think you want something as delicate as an Aibo. What about the Zoomer robotic dog from Spin Master or maybe one of the products available from WowWee? Neither of these products are programmable like the pleo but you could still discuss basic stuff like voice recognition, obstacle detection using infrared, and the various programming languages that bring these hunks of wires and circuits to exhibit such lifelike movement.
Talon