Loved staying at Juliana's place. It felt lived in and cared for and it shows - I really enjoyed my stay.
It was in downtown (centro), walking distance to Lapa and quiet (for the most part - see below), super close to the metro and a Starbucks, so the location was great. There was even a restaurant around the corner that was always opened and had parties on the weekend.
Juliana was super nice and responsive. Also there's a drip coffee maker and great wifi which made working remote awesome.
There are some minor cons - it's pretty quiet for the most part because it's high up, but there was one night where there was a rally for the local football team (Flamengo) with drums right in front of the building that went till 2am. I also kind of wished the couch/futon was a bit softer.
I would book this place next time I return to Rio.