I tried a couple of the "pack my box with five dozen liquor jugs" sentences but couldn't get them to connect together in an all-connected crossword.

I am thinking it might work with one of the following (cut and pasted from http://rinkworks.com/words/oddities.shtml):

Dermatoglyphics, misconjugatedly, and uncopyrightable, each fifteen letters long, are the longest English words in which no letter appears more than once. Fourteen letter words with this property are ambidextrously, benzhydroxamic, hydromagnetics, hydropneumatic, pseudomythical, schizotrypanum, sulphogermanic, troublemakings, undiscoverably, and vesiculography.

I think the most important aspect is to get good vowel separation so parallel words don't rub each other. I'll try some of the above words sometime when I get a few minutes.