One of the discussions I always come across with my customers is to point them towards how Microsoft does things or what it recommends. This is a common scenario and we have lot of stuff on this falling into various categories. However 2 sites I always like and I see many people not coming across them, do check out these:
http://technet.microsoft.com/en-us/library/bb687780.aspx Microsoft IT Showcase: How Microsoft Does IT
Microsoft IT Showcase presents an inside view of the Microsoft IT process for developing, deploying, and managing Microsoft solutions—from Microsoft IT professionals to IT professionals—peer to peer.
http://technet.microsoft.com/en-us/library/cc196387.aspx Infrastructure Planning and Design Guide Series
The Infrastructure Planning and Design (IPD) series provides guidance for Microsoft infrastructure products. The series is a collection of documents that leads the reader through a sequence of core decision points to design an infrastructure for Microsoft products. It also provides a means to validate design decisions with the business to ensure that the solution meets the requirements for both business and infrastructure stakeholders.