Are University Grades or College Grades Important?
If you are competing with others to get into graduate school or a professional program like medical, dental or law school, then university grades are extremely important. The top places will usually take only the top students from the undergraduate years. Some employers such as top accounting and law firms hire only the top students with the top college grades too. So, if you are pursuing fields that require high marks, you will have to maximize your university grades or college grades (do some research to determine if this will be your case).
In addition to good college or university grades, some programs like MBA and law schools will require you to take specific admission exams (GMAT, LSAT). You have to score well on these to ensure that you will get accepted. I would advise you to take these exams as early as possible, perhaps during your summers. This is because these exams have high school math content like geometry, which you may have forgotten. The longer you wait, the more you will have to relearn for the exam. I took a weekend prep course on how to take GMAT and I don't think I would have survived without it since I had forgotten a lot of the math required. If you blow one of these exams, you can usually take them again.
Some programs like dentistry require more than just good grades. For the entrance exam to dental schools, candidates have to do a special carving that tests their manual skills. I know of at least one person who studied like crazy to get top marks but didn't do anything to prepare for the carving test. When he got to the exam, he ended up breaking the carving. This pretty well ended his hopes to get into dental school despite his high academic university grades.
Some folks think this carving test is not fair but then again, I don't think any of us would want somebody with poor manual skills to work on our own teeth. So this proves that for some specific programs, grades are certainly not the only factor that is important.
If the field you are pursuing does not stress high college grades, then I'm going to surprise you with my next statement. Get decent college grades (minimum of B's) but don't bust your butt just to get straight A's. You will be better off being a well rounded B average and spending time to develop other important skills (such as people skills) rather than an A+ bookworm who studies 100% of the time. I have never been asked during job interviews what my university grades were and I became a corporate executive. This is not unusual.
If you feel overloaded with courses during the regular school season, consider taking 1-2 courses during the summers in order to lighten up your course load during the regular school year. I took this approach for two summers and found it helpful in getting my university grades up.
Of course, listening to good external guest speakers on campus will have nothing to do with your college grades but can be important for your future success if they teach you important skills. If you know of any good speakers that have speaking programs that will benefit students, refer them to your Student Activities staff to bring them into your college or university as a guest speaker.