I've made my pitch to my wife to get me the 16gb Zune HD as my Cristmas present. When the kids got my wife a 16gb Nano for her Birthday, it was my job to reorganize her music collection since she currently had 27gb used on the old Picture iPod.
What I realized is that 16gb is reasonable if you breakdown your selections into manged playlists and change them as needed. I wouldn't mind the 32gb, but another $100 would put it outside of the limit my wife and I determine for gifts to each other...
I'm not sure that Microsoft even sees the need for a larger Zune, so I would not hold my breath for one
Steve