The single domain model meet required and one result. The master domain model, whether you assume it is single master or multiple master, does not meet the required results. How can you have centralized users and still have trust relationships of chicago trusting paris and caracas and seattle, dallas, and new york trusting chicago. There must be users in paris, caracas, and chicago and chicago has both users and resources. You have single domain and 1 PDC and 10 BDC's.
Users say logon is slow.
There is too much synchronization between the controllers. If the question mentions no need for intranet then ignore wins and dns. Never choose dhcp. DHCP relay is for doing dhcp over subnets. Rip for IP is to have a dynamic table that tells you instantly if a router is or is not attached.