The biggest mistake I made as an undergrad was studying to get good grades, not to learn the material. Now I'm re-reading stuff in stats and neuroscience as I prepare for grad school because I crammed on nearly every big test as an underclassman.
To answer your question, whatever your end goal is (MD, PhD, MA, MPH, or a Bachelor's in Engineering) approach every undergraduate class like this will be your only chance to have time to study that topic because once it's behind you it all starts to blend together. A major with more rigorous coursework, more laboratory instruction, and opportunities for research and possibly teaching assistantships will best prepare you for a solid job after you graduate (or to get into a competitive grad program). Yes, some curriculum may be harder than others, but if you are serious enough about your education you will take the time to learn and master those topics in order to be successful (the tutoring sessions will become your best friend). In my experience, the students who took the easiest classes to pad their GPA rarely make it very far, it's all dependent on your level of investment. Keep up with the reading, study something every day, and don't put off that paper that's due on Friday until late Thursday night. Then how difficult the class is wont matter because you have made the effort to turn the tables in you favor.