Even if you decide you don't need to use a formal RFP process to make your purchasing decision from the dozens of Tier 1, Tier 2, and Tier 3 ISPs that can handle your locations, you might want to do a draft of an RFP to identify what requirements are important to you and what requirements are less important. That's especially true when you're talking about latency - latency from where to where, at what bandwidths? Some carriers publish "average" latencies, using statistical methods with dubious assumptions designed to make them look good (:-) (My employer's dubious numbers are about 10ms better than some other carriers' dubious numbers, but of course I'm not speaking for them and a lot of the difference is geographical concentration), but for the most part the dominant factors in latency are average distance (speed of light in fiber is about 1ms per 100 miles) and insertion delay on smaller access lines (1500 byte packet takes about 8ms on a T1 - insertion delay is negligible for T3 and above.) If there's a specific destination you're trying to get to, then sometimes peering locations make a difference - if you're in Denver trying to connect to another Denver location on some third-party DSL, are you going through a peering point in San Francisco or Seattle or Singapore? If you're crossing an ocean, does the carrier you're looking at route traffic across the North Pacific or the South Pacific or both? Or are you really more concerned about having an abuse desk that works, or about access line diversity, or is price 90% of the decision criteria, or are you trying to take advantage of different carriers' peering patterns, etc.?