The best UI for a touchscreen is usually opposite of how you'd use it with a keyboard and a tweak on how you'd use it with a mouse... that is not even considering multi-touch, which adds a completely different aspect. Again, look at XPtunes... it is very good, albeit very basic (no eye candy).
Every screen should have option to show/hide direct access to any other area the user needs (other sections, home, exit, etc)
In my case, I only want it for the Audio Library but would like to have one-touch access to multiple views... Genre, Newest, Artist, Album, etc.
The way the normal screen in MC works is actually very close to usable with touch. We'd need to remove the left-side panes, make the buttons a bit larger, and allow the tabs with the view types (genre, etc) "sticky" (not reset when closes/relaunched.
I'm sure several of us could give some input and a great touch screen UI could be designed... but JR would need to be serious about doing it and getting it done soon. If