A card might seem fancy..but this is not a competition nor an interview. Most schools ask you to send an email and if no response call. The key here is effective communication
The big picture here is to contact your preceptor 1 to 2 weeks prior start of rotation to introduce yourself, ask questions about paperwork to bring on the first day, white coat policy, when, where and time of first meeting etc..
With an email you have the proof that you did try to make contact in a timely manner. If something was to come up you are covered. This process also help the school uncover potential problem with the rotation site availability or preceptor availability and make adjustement to your schedule ASAP if there was a need to. Believe it or not sometimes things happen on rotaton sites or preceptor's life that affect students rotations and preceptor forget to mention it to the school.
My stand: go for effectiveness first. Then, after the rotation ends you can always send a thank you note, thanking him/her on how much you learn from them. And finally imagine, how you'll feel if after taking your time to send a fancy FYI card; he or she contact you or contact the school asking them to remind to the student body that they'd be contacted by email for faster, and more reliable communication.
Just some points to think about
