Take special note of the following video:

View on screencast.com »

It shows how to customize the Conditional Appearance module to allow your end-users to easily create Appearance rules directly from Views and not by using the Model Editor tool.

Refer to the http://www.devexpress.com/issue=Q381881 ticket for the source code of this extension. In my opinion it is a very smart piece of work and your end-users will like it.