Costa Rica was great to visit, until I found Belize. East coast of CR is rocky, found the west coast more beautiful with black sand. We stayed in Limon and San Jose, and took day tours to the west coast out of San Jose. Country is so narrow, you can do both coast easily. Good bus system.
Resorts on the NW corner probably are the best. A few years ago, could not get hopper flights, had to use bus.