And please, do not forget to add ACL at all permission levels, buttons, actions, links and not only for main menu/functionality.
There is a work item for it, and it is very important once it is a security breach. User having access to orders, for example, can do everything, mark as paid, cancel, refund... for big stores, it is a real problem.
I know you are working hard for a new admin area, but visual is not main problem, with all respect of course.
I'm able to help you with it, just tell me what to do, once there is a lot of people working together!
Let's do the best!!!