It has been many years since I was doing childrens' shows (schools, parties, etc.).
Among the pleasant memories I have of those times, are of playing-to and interacting-with the kids during the build-up of a nice straightforward trick, and at the climax, hearing the adults in the back of the room react astonished.
--People certainly don't expect a Vegas spectacular for a birthday party, and the adults at the function are sometimes a little smug in their assumptions of the "kiddie show" they're about to see...
Thus I like classic, straight-forward material that fools almost regardless of age...you could say that really DOES "pack small & play big".
A few items along those lines:
Torn and restored Newspaper
Han Ping Chien
and even such workhorses as:
Torn and restored napkin with bluff explanation
Mouth coils with spring-flower climax (ala Patrick Martin, N.Y. Symposium vol. 2)
Whoa! Now I really AM giving away too much of the good stuff!!