I have a lot of extra room for classes. What should I take?
I am surprised not to see getting involved in research projects on your list. At many schools, you can get academic credit for research. It is often no good for satisfying requirements, but that sounds like that's not a problem for you.

Getting involved in research is an excellent way to further your dreams, especially in getting on the track for graduate school. It can also introduce you to lots of interesting material that you would never encounter in a class.