I had a great stay at Omar Do Rio in Copacabana. The hosts are very flexible and attentive, and were happy to help meet my strange flight times.
The apartment was great for a longer term stay, and has laundry, a kitchen, and stable wifi. The location is super convenient within Copacabana and has easy access to the beach, stores, restaurants, and tours if you have any booked. Overall, this is a great option for a stay in Copacabana.