I know you asked for EP stories, but if you're not scared off by fantasy, I'd recommend checking out The Great Zeppelin Heist of Oz, that just went live over at PodCastle. Fun story, and the narration is superb. (Of course, as the editor, I'm biased.)
(I also wouldn't actually recommend Sundae for most kids - no offense to Cutter McKay. It does have an ass-kicking teddy bear, but it's extremely violent, and there's some other very R-rated stuff. But if you want more suggestions for fantasy, I'd be happy to give them.)
Uh, other, actual EP stories...
A lot of the stuff by Mike Resnick: Barnaby in Exile, Soulmates, Travels with my Cats
Hesperia and Glory, by Ann Leckie
Tideline, by Elizabeth Bear
Edward Bear and the Long Walk, by Ken Scholes
Will You Be An Astronaut, by Greg Van Eekhout
We Go Back, by Tim Pratt (I'd say Impossible Dreams, too - but the cinematic context of that one may not be as enjoyable for a younger listener? But it's one of my faves.)
Midnight Blue, by Will McIntosh
Clockwork Fagin, by Cory Doctorow
That oughta get you started
