I'm trying to create a site with a common theme or look

I'm trying to create a site with a common theme or look and one central area for client management (client's have wordpress user accounts). The site will be specialized for different states.

I believe subdomains have better SEO value than subfolders, so I was wondering, is it possible to setup a single WP site with support for different content in subdomains? So for example, texas.mysite.com would have some content different from florida.mysite.com but login and custom functions would be at mysite.com.