Standardization and modularization go beyond the same server form factor. While it may have made sense in the mainframe era to design and build data center physical systems to meet the unique needs of the installation, it makes zero sense now. With standard-size racks housing standard-size servers, you can certainly meet your needs with standardized power and cooling systems.
Almost every power and cooling vendor today will work with you to preconfigure systems. Just like car shopping, you pick the model and color and choose from a few option packages; the rest is standardized. The result is a system that's less expensive to buy and own and that behaves far more predictably than its custom counterparts--so much so that the physical room itself need not even have been designed to be a data center.
Particularly for small and midsize data centers--say, those less than 3,000 square feet--the raised floor may no longer be necessary, and in fact you may be far better off without one. In-row and rack-based cooling systems provide the modularity needed and can be deployed in almost any interior room. It can be as simple as this: Get the physical security right, make sure you can pull enough power and access for external chillers, then have your modular data center dropped off at the loading dock.