We found this through TripAdvisor reviews and were not disappointed. It's on the lava side of the volcano. Although we didn't see any lava for a week, the view was outstanding from our room and there was a lightning storm that was as good as any we've ever seen. We ended up booking an extra night because we were so happy with the surroundings.
First, 4x4 rental is almost mandatory to enjoy this area. The hotel is easy enough to find, but it's a bumpy 10km ride from any paved road. That said, we had a lot of fun with our Rav4 (rented from Alamo). One traveler tip - pay extra for the "zero deductible" insurance. You can bring your car back on Empty and not worry about any stones being thrown up from other vehicles. It's peace of mind for $20 extra per day.
Staff here is outstanding - from maid service to servers. Bernardo at the front desk is a veritable treasure trove of local knowledge, booking us on a horseback riding adventure to a newly discovered waterfall. While the trails were not yet well developed, this is the type of experience you want when traveling to Costa Rica.
And, make sure you take a side trip to Pizza John's just up the bumpy road in a small village past El Castillo. While almost impossible to find, it was a great $15 meal (including drinks). No better recommendation was that we saw 3 staff from our hotel ordering take out pizzas at various points during our meal. All 3 stopped to visit with us while they were waiting.
Breakfast was great, but dinner at the hotel is expensive compared to local options. La Fortuna is less than 30 minutes away (which is why we recommend a rental car).
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC