Once you have a good understanding of your overall needs in terms of amperage/load you need to look at ease of distribution and the ability to expand or change your setup.
Typically, most small datacenters or for those who have not built them, the company will underestimate not only the amount of power needed but also how the power will be distributed. A datacenter and the hosting industry are constantly changing environments you have to plan your design to be flexible, and if you can afford it, slightly overbuilt.