Barra da Tijuca is great!
The flat it's actually located at "R. Dep. José da Rocha Ribas, 184", just 200m to the beach. They have free umbrellas & chairs. Also swimming pool, tennis player. etc...
Downstairs there are some shops, supermarket & bakery.
Bring some plates if you want to use the kitchen because there were none when we were there. :D