From my limited experience - I'm at best on the periphery of dealing with AWS support; I can characterize aws support as such -

Free tier - occasionally get answers. answers are generally vague. questions to forums. Paid tier - always get answers. answers are generally vague. you get a support portal. Top tier paid - always get answers. answers are generally vague. amazon employees will fly out to your site to give vague answers.

We did. And we were paying enough (6 digit monthly bill, not huge but significant I would think) that we did get some nice treatment, although we were definitely not a big enough customer apparently. We adopted a lot of things right away when it came out (ie windows instances, elb). I think that was a mistake and lead to a lot of issues that resulted in responses acting like its not a problem until 6 months later when a fix came out. EC2 was a lot better then my experiences with Terremark though, but we were definitely pennies to them.