I don't entirely understand the OP's desire for east coast locality. Maybe it's because my sites are accessed from a variety of locations around the country and around the world, but it seems like a zero sum game where a west coast datacenter means west coast users have 30ms latency and east coast users have 90ms latency whereas an east coast datacenter means that east coast users have 30ms latency and west coast users have 90ms latency.
In the absence of a sophisticated edge network, thinking about latency in terms of where a datacenter is located is a zero sum game if your users are geographically distributed.
If ultra-low latency is the OP's desire and all his or her users are on the east coast, then I hate to say it but finding a host with a datacenter on the east coast might be the only solution.
Generally, though, I'm with sXi in wondering how latency could be such a big issue?
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