Guides would be a useful addition.

The object alignment functionality is great, and makes it easy to quickly layout a design. But I would like to have guides to help define some global layout markers, and have objects align to the guides. I usually need a gutter around the edges of containers or between columns, and with objects that aren't left aligned it's very difficult to maintain a consistent alignment. For example, I might create a form with right aligned labels. If I put two forms on a page it's currently pretty hard to get consistent label alignment across the forms.