i'd have to say it's a tie for me.
one we did that got kids of a fairly wide age group (~5-14) involved was at a law firm. they invited us to come and demo, and after we talked a bit and showed the robot we did a sort of relay race thing. there were two kids per a round, we gave 1 a triangle, 1 a square, and then put 2 circles in between them. the first one to hang their shape and then run back and get the circle and then hang it won. it was very entertaining to watch. we made the older kids go for the top, which was great to watch! and we picked on some of the adults there too....
we let some of the older kids (and an adult) drive the robot.
another one was at a senior citizen living community near us, it was great to see their faces light up that kids could build these things. they asked a lot of questions afterwards. i think we instilled some hope in them for our generation, which was great to see!