DaveR- that is true there is a button in the default toolbar for Zoom Extent.Zoom-Zoom (and Keeping it dialed in)
I see a lot of great Sketchup tutorials online (here and there), and while they do discuss different techniques, tools and what not - you really have to follow through from start to end, and go along a somewhat complex path to get the hang of things. one more thing - while on that road - one's eyes are focused on the end result, and sometimes one can miss the fantastic little tips along the way.
This tutorial is one of many short - tip/tool specific - tutorials that can help people get around Sketchup and have an easier time around.
Zoom and Center ALL
Sometimes you add a new component to your model (or you're working inside a small part (zoomed in)) and want to see the "whole picture" zoomed across the entire screen, and centered.
This is possible using the 'camera-zoom-extent' feature. click the zoom-extents buttonor press SHIFT+Z (this is the default hotkey) and Sketchup will zoom and fit everything in your model into view and center it across your screen:
Zooming and Centering Specific Parts in your Model
Sometimes you want to zoom and center on a specific piece in your model (a specific component, or a specific surface/line/arc/circle/etc). Sketchup can do that too.
Select the part you want to zoom and center upon (in this example, it's the circle for the hole):
right(ctrl for mac)-click on it, and select "zoom-extent", it will zoom and fit that part in the center of your screen:
The later zooming technique is referred to as 'edit-zoom-extent' and can be assigned to a hotkey of your liking- more about that in a later tutorial.
I find that using hotkeys is the way to go (Photoshop, Maya, Final Cut, Sketchup, you name it) I dont like searching around with my pen/mouse for buttons to click when I can blindly click a hotkey instantly - or better yet - a sequence of hotkeys. this is the equivalent of creating a rectangle in Sketchup by clicking, dragging to the exact sizes in both dimensions, clicking - OR - clicking, typing dimensions, and pressing Enter gotta love speed.
I personally hardly ever have toolbars visible on screen (this tutorial wasn't done on MY computer) I find that they take off too much of the real estate that can be used to see more of the actual work surface. I use hotkeys religiously.