I am looking for suggestions on good themes for med to large sites that will have no trouble updating everytime wordpress updates.
You may try this if you don't mind purchasing it. But I don't have personal experience with them. Check all details before purchase. http://www.revolutiontheme.com
WP Remix and all the Revolution Themes are quite good. Revolution Themes are now free as long as you can figure out how to modify them, otherwise you purchase the "support" for the theme.