Is there a host side viewer that allows a website visitor to pan, rotate, change elevation, and zoom in/out on a SketchUp file? Preference is one that works on mobile platforms without the need to install an app.
What is a host side viewer? I suppose your website visitors are clients?
And what do you think of when you say plugin viewer?
If you can put your model into 3D Warehouse you could use that viewer. Try this as an example:
You can orbit and zoom in and out, and with the shift key held down you can pan in four directions.
Unfortunately, although the player could work in iOS 8, it’s disabled for mobile, so for now this will just do for desktop.