This may not be applicable, but if I were making an all-ages show, I'd either make the framework kid-friendly (as in, making with the kid logic), and make the jokes more adult-friendly, or go the other way around.
I always remember an episode of the Simpsons I watched with my nephew a few years ago. Bart and Lisa got lost on a field trip, and Milhouse is named the proxy Bart. When the kids find their way home, and Milhouse realizes he can't be Bart anymore, he says "Ay Carumba!" I laughed because of the references to the one-time Bart catchphrase, and all of the other jokes layed in there. My nephew, who was eight or so at the time, laughed, too, but it was because he thought the catchphrase itself was funny.
I also imagine that if you put in the adult-level dialogue -- not "adult," but sophisticated and intelligent -- the adults will respect it, and find the humor in it that you want, and kids will feel like they're being talked to honestly. I'm sure that when you were a child you liked seeing the precocious kids on screen, the ones you imagined you and your friends were like, rather than the shows that talked down to you. Kids are much more interested, as far as I'm aware, in content meant for a couple years above their age, rather than content meant for their age.
Don't know if that would help at all, but hopefully it does.