Option to keep spoken word/comedy/audio book tracks out of Main Library, to improve Random Music

I often put itunes on 'Random' within Music. I often have to press 'next track' when a spanish lesson track, or equivalent, is selected by the random generator. I would like a way to file these in a 'not for random play' category, or perhaps most simply, to tick ('check', for US readers) a box in preferences that says 'exclude spoken word/audio books from random play' . Anyone else?