If possible, we like to travel with a large backpack rather than a suitcase while in Costa Rica. It just makes life easier if you are visiting multiple spots.
Most accommodations don’t have elevators so it is much easier to get up and down stairs with a backpack.
Also, the sidewalks here are often horrible. You don’t want to be wheeling a suitcase and have a wheel pop off.
This is especially important if you are planning to backpack through Costa Rica and possibly visit more Central American countries.