*My first wish would be to have Maya 4.5's Smooth Proxy to have all the functionallity of CPS tools (particually mirror and stitch) and most importantly, have the ability to crease (both Full and Partial) in Smooth Proxy.
*I would also love an Attach feature like max's where you don't have to Combine and then delete the history. Instead you can just have an Attach Tool where you select a poly object, hold down Shift and select another poly object, press enter or Y, then it'll take all the polys from the latter selected object and create them in the object first selected. You could also have tool options saying whether the attached object is deleted, hidden or shown.
*Skeleton primitives would be great, something that you can quickly create and edit, and not worry about whether you made a mistake. You should be able to choose from a selection of different skeleton types, and have skeleton segment options like Max's Biped. It should also have other options like to have it set up with IK handels, etc