We need to be able to toggle between display modes.
If you're working on a tspline surface and making subtle changes, you need to be able to toggle between "shaded" and "shaded with visible edges" or similar. Look at "toggle model" in Alias.
This needs to be done fast, preferably with a hotkey (really we need to be able to map our own hotkeys for everything).
By having to do this with menus, it takes an enormous amount of time as I literally have to do this hundreds of time a day.
It's not possible to get decent visual feedback on a surface with the wireframe in the way.