You can try Arcade Music Box (even I have discounted it)? Even it list based, it switch coverarts when you scroll trouch folders in a list. Hince they should only look on the coverart and the song number remembed. I remember it was a succes with kids in that ages from a AMB users I have.
MultiJuke could been more kid freidly, which I might working on. BTW it mere about adding songs to queue, and where it play it. I guess limits the queue or changing to 2 song queue system would been good idea. Arcade Music Box have both features (but NextSong is not really in MultiJuke, unless you use Credits mode, hince it would been fixed).
You can let me known, what they want in MultiJuke to get 100% kid freidly (even the GUI is really simple to use).
Wincab, using Album skins is a another idea?