Here's a little secret. If you are planning a trip to Costa Rica and want to experience both The Pacific Coast and the rainforest/Arenal area you can split up the 3-4 hour commute with a 2-hour, exciting rafting trip on the Rio Tenorio! The highlight of this particular rafting tour is a 12-foot drop at the end of the run... and if you have Weider (aka "Chewy"/aka The Terminator) as your raft guide be prepared to flip and take in some water! This is a rafting trip for the more adventurous traveler.
Note that after the rafting trip you will need to drive 40 minutes along an extremely bumpy, unpaved road to get back to the base/restaurant where you will get your traditional Costa Rican cuisine lunch and then be transported to your final destination of either Arenal, Tamarindo or San Jose (all are about 1.5-2 hours away).