With multisite, the Group Policy infrastructure becomes a little more complicated. As opposed to single-site, where everything goes into two policy objects (server and clients), multisite needs a separate GPO for the server of each entry point, and a separate client GPO for each domain. If Windows 7 clients are also a part of this, then you would need a client GPO for each entry point and each domain for the Windows 7 clients. Let's say, for example, that your company has a site in the US, Europe, and Africa, each with its own domain and servicing both Windows 8 and Windows 7 computers, and with two entry points in each continent. In that case, you would have:
six server GPOs (one per entry point)
nine client GPOs (three GPOs for Windows 8 clients and 6 GPOs for Windows 7 clients)
When you create the multisite configuration, the URA wizard creates everything automatically, unless you specify otherwise. This could become a little tricky, because creating all the policies...