Since our group of 4 did not have a car, our criteria for a hotel was walking distance to restaurants, as close to the beach as possible (most of Manuel Antonio is up on a hill above the beach), and third was a pool if possible. Mango Moon was all of this and more! The hotel has walking trails to two beaches; one-the private Mango Moon beach is a beautiful ~15 min walk to a white sand beach with gentle waves perfect for swimming. The other is the less busy northwestern end of the main Espadilla Beach, also a ~15 min walk or ~10 min taxi to the south end with access to restaurants, beach vendors, and surf school or boogey board rental.
We stayed in the Iguana Pad. Excellent AC in both bedrooms, hot water showers, and very clean. All of the rooms appeared to have ocean views so I don't think you can go wrong. The pool and open air restaurant/bar also overlooked the pool and ocean and the food was excellent. Try the Mango-tini! There was an excellent guitar player one night. The music ended at 9:00 so we did not have problems with music noise that other reviews mention. All of the staff were super friendly without exception, and spoke good English and were very helpful in arranging adventures for our group.
TIP: We flew out of Quepos Airport (~15 min taxi ride) on Sansa Airline. For $50 a person and 25 min flight to San Jose it gave us awesome views over the beaches, palm plantations and approach into San Jose and allowed us to spend a few more hours at Mango Moon. I highly recommend flying as an additional adventure!