My company operates a SaaS product. My charge is our corporate environment, i.e. users, computers and the Data Center at the Corp office. I am planning to upgrade our current Active Directory structure. I have roughly 65 users where 60 work from our Corp office and the other five from their respective Home Offices. I have five data centers geographically dispersed with their own AD Forest. I would like to pull everything under a single forest. What is best practice here? Should they be their own independent Forest or should they be Domains under a parent forest. Keep in mind all access to the other data centers are accessed from the Corp office.
Also would it be better for me to Upgrade my Current Active Directory environment by promoting up or start from scratch? What are the pros and Cons of both?