I'll be entering my last year for my BS degree in physics this fall. I have Solid State lecture and Solid State Lab lined up for my physics courses. My friends are taking graduate level Quantum Mechanics. My reasoning is "I already know what QM is, but not SS, and I have to take QM anyway in Grad school." Their reasoning is "We like QM." Is there any advantage to taking grad level courses as an undergrad vs. expanding my undergrad knowledge library? Especially if we consider that it will be harder for me to get a good grade in grad level QM than undergrad SS. I've already taken Statistical Mechanics, so I have a small taste of SS. I'm mainly doing it to boost my GPA a bit. The Lab is required, though. Should I switch lectures?