Bulk Plan Clustering Design inputs needed.

I am trying to come up with a design for a customer who is using single instance of OTM across 3 regions.
My initial analysis suggest that a process which can marry 'Domain Clustering + 'Functional Clustering' + 'High Availability' models and come up with a solution which would be ideal for the customer.
Customer has 1 instance of OTM and is being used across 3 regions. He is not happy with his current model and wants to improvise and make best use of OTM's scalability.

Any inputs on this would be of much help.

Thanks much.