I've Been 47% of Everywhere, Man
create your own visited states map
or check out these Google Hacks.
The above is a map with the states I have visited in red -- which does not necessarily mean they are "Red States." I'm pleased to say that I have managed to spend at least a little time in most of the parts of the US I'm interested in visiting. I'd certainly like to see more of New England (and Pennsylvania, which I gather is not considered part of New England really), and I'd love to go to Hawaii and Alaska, but I must confess I have only passing interest in seeing more of "middle america," and if you read this blog regularly you can probably guess why.
If I happen to get the chance, I'll travel almost anywhere someone wants to send me -- I love new experiences, even if I'm not sure they're going to be good ones -- but everyone has prejudices, and most of the states I've not been too are, I believe, too full of stupid people to bother with sorting out the gems (and I'm certain each of those states has little gems I'd be delighted by, I should add).