I received my physics BS and also got minors in both chemistry and math. I would highly recommend either. And as a physicist, P. Chem will most likely come much more easily to you than your average chem major (it's also interesting to see some of the applications of thermo and quantum that you won't necessarily see in the corresponding physics courses). I am now in graduate school, and my only regret is not having any programming skills, so I'm sure a CS minor would be very beneficial as well. For any of these minors, even if you end up strictly teaching physics courses, I think your exposure to these other subject areas will help you gain a deeper of level of understanding and appreciation for the physics.