Back in the 1990s, when I was teaching Introductory Psychology, I invited my colleague, Jeanne Day, to give a guest lecture on social intelligence. It was so fascinating and good that all 160 students applauded when she finished. She must have felt so appreciated.
The reason I mention this now is that you are about to get the chance to express appreciation for your great professors, as well as to criticize the poor ones, on your Course Evaluation Forms (CIFs). But why should you stop there? If you want to applaud your professor, go ahead. If you want to give a small gift or leave a thank-you note, do it. You will feel really good about yourself for making your professor feel appreciated.
but how do you do it without seeming like you’re sucking up to him/her, either in your professor’s eyes or in the eyes of your peers?
Professors won’t think you are sucking up when you express appreciation. And if the professor truly deserves your appreciation, the other students will recognize the correctness of your expression of gratitude. It might inspire them to express gratitude toward their professors, too, which is good for everybody!