It just depends what fits your content best. Just try out several, and see if they can be tailored to your needs. I try to keep my themes minimal. I use wide open spaces, and organize everything in these spaces to really help the content pop out. Focus on your content.
After reading through your thread you say you will have two sides. I'd have one that uses SSL and one that doesn't. One of the mods has a really cool example of WP running with and without SSL.
Check out dembowski.net
She has a web-server running with one instance of WP using https and another not using https. I think it is a very cool example.