First of all — congrats on the interviews! I talked to several people who were applying to medical school and PhD programs last year for Fall 2019 and the individuals that had 4+ interviews always mentioned how overwhelmed they were. From the cost of flights, to traveling, to missing work and having to play catch-up afterwards, they hated it! At the end of the day, it really is about fit, so definitely decline any offer for a school that you don’t see yourself at for the sake of your sanity. Mental health is VERY important through this process. Good luck!