I must confess that I do not use coffee cup as my main website.
Aww... that makes me sad.
I do use it for all of my "client" pages.
Yay! That makes me happy!
You could possibly do something like that in the future, but for now S-Drive sites are intended to be one site per URL. Now once Direct FTP and the HTML Editor are S-Drive enabled you could easily use a structure.
What might be easer, though, would be to create a site for each client (e.g. client1.coffeecup.com, client2.coffeecup.com, and so on). That way each client could have their own Stream, Site, and other services on a case-by-case basis. It would help prevent mixups, and you could manage all your clients together via the control panel.
You can't do this yet, but multiple S-Drive accounts are coming very soon.