Selecting an appropiate colocation offering involves more than just picking a 19 inch rack at a random data center location. As the cost of electricity is an important part of overall data center costs nowadays, one should definitely be informed about the energy-efficiency level of a data center premises. A Power Usage Effectiveness (PUE) figure may provide a fairly good directive.
Connectivity is another selection criterion. Some data centers have limited connectivity options available, with not so many IP transit providers present. Others are located at internet hubs, with multiple IP transit connections onsite. If you’re a high traffic user, available peering options as well may constitute a decisive argument for choosing a specific data center location. Also, does the data center provider address your needs regarding UPS redundancy, cooling and power feed scalability as well as timely engineering support?