There are not a large number of direct flights to SJO so you will likely have to go to New York, Charlotte or Miami before heading down to San Jose. The flight time from Charlotte is right at four (4) hours. I went during the COVID Pandemic in April 2021 yet the flight was completely full on the way there and on the way back. Do not think you are going to get a flight where you have an entire row to yourself. I flew American and that seems to be one of the only United States carriers that has trips to San Jose. There are no Southwest flights to SJO (San Jose)
When flying into San Jose, American Airlines will tell you that you need to be at the airport three (3) hours before you depart on your flight back. Once again, I took this flight during COVID and I know there were precautions but it took no longer than an hour to get into the airport once I walked in from the Avis Shuttle dropping me off at the front door. I even had to provide a negative COVID test to two different attendants and it still only took an hour total.