Monteverde is nice but better for the occasional hiker. There are a lot of reserves to hike there, but most of them don’t have 6-12 miles of trails to explore. Plus like you said, it can be crowded. We love hiking and in our opinion, the best place in the country for it is the Southern Zone. That’s the coastal areas around Dominical, going into the mountains of San Isidro del General, up to Los Quetzales National Park. If you based your time out of this region, you could visit:
- Costa Rica’s highest peak, Mt. Chirripo– Takes at least 2 days to hike; there’s a ranger station near the top to overnight
- Cloudbridge Nature Reserve in San Gerardo de Rivas– Great spot for moderately difficult hiking. It has a mix of cloud forest and rainforest so is a really great place to see birds and other wildlife. Not crowded at all. Here’s their website: http://www.cloudbridge.org/
- Los Quetzales National Park– Way up in the mountains- cloud forest habitat; a great alternative to Monteverde and has some shorter trails as well as a longer one that leads to the very small town of San Gerardo de Dota. We wrote a blog about it here: https://www.twoweeksincostarica.com/costa-ricas-other-cloud-forest-los-quetzales-national-park/
- Smaller reserves around Dominical- Hacienda Baru (https://www.twoweeksincostarica.com/hacienda-baru-wildlife-refuge/), etc.
Another option for longer hikes is Corcovado National Park, Costa Rica’s wildest park, on the Osa Peninsula. It has a huge network of trails that take a week or more to hike but you would need a guide because one is required to enter the park now.
Hope that helps! We do have a chapter on Eco-Trekking in our Top 10 Costa Rica Itineraries book if you want some more ideas. Have a great trip!