Individual dimensions vary, but as a 6'4" person myself I can say there is plenty of headroom in the CLK, C's, and E's. The SLK does not have enough, especially with a competition helmet on....

As for the paint, I've noticed that many of the newer cars have more orange peel and minor defects than the previous cars. Don't get me wrong, most still look great, its just that I'm seeing more of the newer cars having minor defects I don't think would of made it out of the factory 7+ years ago.

Personal tastes vary, but for the cost I'd go with the CLK55 or E55 first. There isn't a bad choice among them though, it just depends on what appeals most to you.

Hope this helps...Lee