I stayed at both Sheraton Rio and Sheraton Barra last June. Some work was going on at the Rio but I had a decent corner room, upper floor, with great views of the sea and beaches with a balcony wrapped around the corner. They have a shuttle that runs to a shopping mall that makes stops along the beaches. Took a taxi to the Barra, about 30 real, but the taxi drivers don't seem to want to use the meter and the price list posted in the back seat wasn't being adhered to, at least with their opening offer.
The Barra is newer and in better condition, but this is quite a ways away from Rio. Also, on the way to the Barra, noticed that the policia sent up checkpoints to seach vehicles heading in the Rio direction. Taxi driver mentioned that there is frequently a delay. Not much out in Barra except a very good beach. I had a nice suite, lower floor, with a balcony with a sea view. Restaurants are as expected, nothing worthwhile. Small pool and fitness center. In "town" a Hard Rock Cafe and a good steak house a few blocks (long walk) away in the commercial zone. The only problem I had was the airport shuttle I had the conceirge arrange for the return to the airport. Probably too cheap to expect them to run on time, plus, this is Rio. Waited 1.5 hours from the scheduled time to get picked up. Had I known, I would have just gotten a taxi and paid the extra cost. Though, it all worked out, as I didn't have to spend too much time in the substandard Admirals Club at GIG.