San José is likely where you'll arrive in country, but don't rush away! It has SO MUCH to offer!
This quaint town is near the Arenal Volcano and is a great spot to stay for a bit if you want to avoid the hustle and bustle of a bigger city.
Nature lovers will be tempted to settle down and stay in this gorgeous setting. The Manuel Antonio park is full of flora and fauna and is a whole experience in itself.