I'd like to bounce this around WHT for a while: what would your dream control panel have? Assuming you have unlimited resources (can hire unlimited staff and have unlimited hours in the day), what would you like to be able to do in it? What kind of interface would you like it have? Finally, what backend server software would you like your dream control panel to control?
In answering this, take into account what your clients would like to do with it, and take into account any issues you may be having with your current control panel. Also, if you do VPS/VDS hosting, what would you want to be able to do in your VPS control panel (ServerXchange comes to mind when thinking of a VPS control panel)?
Thanks in advance!