I know layers/groups are a ways off, but here is what I'd like to see...

Groups:
*You should be able to group objects together, and manipulate them as a whole wrt rotation, scaling, clipping, etc.
*Groups should be able to contain objects in different layers.
*You should be able to hide/show groups
*Groups should be lockable so that they can not be operated on.

Layers:
* You should be able to assign an object to a layer
* You should be able to lock and hide/show a layer.
* Objects not assigned to a layer, by default are part of a 'default' layer that can be locked, hidden, etc.

Colors:
* Assign a color to a object, group, or all objects in a layer.

Why layers/Groups?

Well, with even moderately complicated models, I find myself constantly pushing curves out of the way, or trying to make do with just the global show/hide.
With layers, I could lay out all my contours on a a plane or so, group them, put them in a layer, set it's color ( light grey ) and lock it. Now I have a reference for my further work.

:)