In planning my upcoming trip, I found that Sansa, Taca's regional airline within Costa Rica, offers unlimited one and two week air passes for $199 and $249, respectively. Might be worth looking into for people who don't want to rent and drive a car.
https://www.flysansa.com/promo.html
Wish I had known that Taca had this subsidiary before booking my final trips on the off chance that GP would have allowed intra Costa Rica segments as part of my awards. Too late now, I suppose.