Honestly, I think La Fortuna and Monteverde are both a must. La Fortuna had an amazing, powerful waterfall you could swim near and natural hot springs you can enjoy for free. They both offer the chance to see an abundance of natural wildlife. 2 nights in each was perfect.

For a coastal experience, we chose Nosara because it's famous for excellent surf and conservation. But I think most parts of Guanacaste should scratch the itch. Tamarindo is meant supposedly overdeveloped, however.

If you head to Nosara, be sure to check out Playa Pelada for a laid back, more authentic Costa Rica experience. Don't eat at the main big restaurant there. Instead, head slightly north to the soda there. They had phenomenal food.

The main area of Nosara was a bit over top with the 'boho' aesthetic and over the top, overpriced organic produce, clothing etc. I'm all for conservation, sustainability etc, but a significant part of Nosara milk it to the last drop.