I'm in the process of creating a resellers host site. The question is whether or not to set this resellers hosting site up with a new domain to use my primary domain and create a sub domain? I think of it like this. What would the big boys do. If Yahoo of Google would set up a hosting site they would more then likely just ad a sub domain as they have now pages.google.com and smallbusiness.yahoo.com I know there maybe an argument about whether or not use a different or new domain however my opinion is to keep what you have that works. What is your opinion on using a sub domain or getting a new domain for hosting?
Well Big Players like google like to use thier brand to promote thier other services but they also use real domains for services like gmail, youtube
It depends if you will ever want to sell one of the businesses? A separate domain will make that much easier.