You're familiar with Illustrator's View > Outline/Preview (Command/Ctrl-Y) toggle, yes? Normally you work in Preview mode, but when you need to edit "the bones" of an illustration, Outline mode is a keystroke away. It's like a wireframe view of your artwork, showing only paths (no fills, no strokes) and live type in pure black and none.
It's been around forever. We jaded veterans can remember when you could *only* work in Outline mode, and Preview was for sissies.
If you only use the menu or shortcut to switch modes, you might think Preview/Outline is an all-or-none choice. Either every bit of artwork is in Preview, or every bit is in Outline. Take your pick.
Actually, that's not true. In either mode, you can Command/Ctrl-click a top-level layer's visibility icon (the eyeball) to switch the contents of just that layer and its sublayers to the "other" mode. So some layers can be in Preview while other are in Outline! It's fantastic when you're trying to align artwork to paths that are obscured by overlapping fills, picking up colors for a gradient mesh, double-checking that your artwork fits within die-cut tolerances and so on.
In "combined" mode it can sometimes be difficult to tell if a layer is in Preview or Outline mode. In that case, just look at its eyeball. When you're in Preview mode, and you've invoked Outline mode for a top-level layer, its eyeball icon loses its fill and turns into an outline of an eyeball! (So clever, those Adobe engineers.) It works vice versa, too — in Outline mode, where the top-level layers automatically show the outlined eyeball (ever notice that?) — the layers you've Command/Ctrl-clicked into Preview mode get filled eyeball icons.
I think most Illustrator users know the program has a New Window command (choose it from the Window menu), which provides another view of the active document. You can put one window into Outline mode and other other into Preview, and the edits you make in one view are immediately done in the other, like an invisible hand.
It's useful, but since Illustrator lacks any Arrange/Tile Windows commands, it takes some work to resize the windows and position them side by side. (A hint here is to resize the main window first, so it only takes up half the space on the monitor, before choosing New Window. Since the new window defaults to the same size as the existing one, you can just slide it over.) Even then, trying to work with two regular windows open side-by-side can be difficult on a smallish monitor.
There's an alternative. If you're in Outline mode (for the whole file or just certain layers) and want to see a concurrent, dynamic color preview of the wireframe art without opening another window, go to the Window menu and choose Navigator.
Normally, you use the Navigator panel to help you, um, navigate the artwork. It replaces having to use the scroll bars and zoom commands. The panel's red-colored View Box can be dragged around in the panel to change the focus in the document window, and it has a view scale slider to change the zoom level.
But who cares … most people use keyboard shortcuts for that, I think. What's key here is that the Navigator panel always shows a *preview* of the entire file, no matter which view mode you're in. The previewed artwork starts out small, but only because the panel is small. To see a larger preview, just increase the size of the panel itself, to the size of your entire monitor, if you want. Though that would make it difficult to edit the artwork. ;-)
So while you're working in Outline, you can see a live preview of your actions right in the Navigator panel. Stash the Navigator in your panel dock, save it in a custom Workspace (Window > Workspace > Save Workspace), and you have another convenient tool to add your Illustrator arsenal.