I use xhtml transitional, myself. Transitional, not strict, because I don't HAVE to separate all style from content. If I want to throw in a quick inline style, I can and the page still validates.
Here is my take on validation. I believe it's a tool to assist you in rendering the page correctly across all platforms. I try to make sure my page all validate but sometimes, like with the embed tag, it won't validate. And that's OK because it doesn't affect how the page renders. So I'm not a stickler that every page has to validate - just because.