Hello there!!!
I would definitely recommend you to rent a car for your visit to Costa Rica. A small 4x4 will be handy and affordable. And you will be able to go any where at any time without depending on the scheduled transportation.
Please let me know if you need any other suggestions or information for your vacation planning in paradise.
Best regards from Costa Rica,
Humberto Gonzalez
Travel Advisor
www.Montezuma-Hotels.com
www.ZumaTours.net