I've used many programs for years that have the following zoom features:
1. Zoom to fit window
2. Zoom selection
In ViaCAD, you hit command-F (or ctrl-F on Windows) to Zoom the item(s) on the build surface to fit in the window. Very fast and convenient.
Zoom selection will Zoom to fit the selected item in the window, so you can detailed view of a single object when you have other objects around.
Similar features are in almost every vector drawing program I'm encountered. It would be a great addition to Simplify3D.
Thanks.
-Howard