If you are not going to install SMS to automate your infrastructure management, then you will most likely be using GP. Read this paper to get some insight about how Microsoft IT uses GP inside Microsoft, including some insights into designing the infrastructure the right way for smooth operations. 

Group Policy Object Infrastructure Management at Microsoft
Detailed discussion of Microsoft IT’s experience in using and managing the Group Policy feature of Active Directory. Streamlined management of the Group Policy Object infrastructure has resulted in enhanced consistency of business operations and regulatory compliance, reduced redundancy, and reduced human error.