I don't know if this is just coincidence, but I seem to be able to get my sites/pages that are strictly straight html to get listed and rank higher than the sites where I have used css. Is there any reason why this would be? I have a couple sites that are css that I'm having trouble getting ranked well for their keywords, while my other html sites were listed quick and are ranking pretty well.
It depends if you use <h1> (etc) heading tags. If you were to use <span> and CSS for headings that would hurt your rankings but <h1> and CSS is fine.
there are two factors reason for you to rank.. on page and off page, having pure html i think was not bad, and maybe you do your link building well so therefore reason for you to be number 1 in serp.
I do the same link building for all of my sites really. It's just that the html sites were indexed very quickly and are doing well for their keywords, but my .css sites are struggling for their keywords. I use the H1 H2 etc on the .css sites.
Theres no real reason why a CSS site should do any worse then an HTML site. In fact it should do better with all other factors being equal. A CSS site should have less on page code (assuming you are using external Style Sheets) so that will allow your content to stand out more and your code-to-text ratio will be better then it would on a straight HTML site.