I don't want to be a hater, but I have a hard time understanding why Manuel Antonio is a must-see. To me it is one of the most overcrowded areas I have ever been to. Yes you can see spider monkeys - sitting in a tree, munching on handouts of oreos. The area is beautiful, the beach is beautiful, but the whole area is overdeveloped. Not saying that you can't or won't enjoy yourself, but I'm not sure you must see it to make your CR trip complete