"Best practices" really depends on your environment and need.
But could be a recommended practice.
I've write this doc from my experience, but also from some doc that is not public available.
In the vSphere Design official course, the solution with a VM for vCenter (not necessary for all services, like DB and VUM) is recommended.
For large environment is suggested to use "management" cluster (with 3 nodes) for vCenter and all the management VMs.
Andre
Andre | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro
