Interestingly, I have a iPad that I am programming this month into a Crestron control system. Not sure I have 100+ hours to develop a perfect GUI for it from scratch, but the client will gain control of their 8 zone system in their home and get all the added benefits of the iPad on top of the Crestron interface.
Instead of a $2,000+ Crestron touchpanel, they do it with the iPad and a $100 application from Crestron. Still, pricey for the Apple store, but cheap in the world of Crestron.
Oh, and don't forget the dock to match!