Are you missing that option in Sketchup – Isolate Selection. You can hide something but not the rest of the model. So good news. There is a simple plugin which adds another position in right-click menu.

You can download it from that web page or directly from here: isolateselection_1.zip

To instal any Sketchup plugin you need to copy it (extracted) to a Plugins folder in Google Sketchup main directory. Usually in Windows 7 it is: C:\Program Files (x86)\Google\Google SketchUp 8\Plugins

I know. My right- click menu is quite extensive 😉

They are other ways to hide automatically not edited objects.
Go to top main menu View –> Component Edit –>…