Per US guidelines COVID-19 tests are required upon departure in order to return to the US. The resort will provide up to 2 free tests per room. Any additional tests will be $19. Schedule your tests at check-in. You can stay updated on the guidelines at https://mx.usembassy.gov/covid-19-information-for-u-s-citizens-in-mexico/
The only additional costs would be excursions and spa reservations.
BRING SUNSCREEN!!!! It is expensive at the resort!
Highs will be in the 80s and lows will be in the 60s