Even if it's cloudy, you may find out there's nothing like the beach for a perfect Sunday in Rio de Janeiro. No matter what time you get up after partying on Saturday, get out and enjoy the shoreline.
The avenues along the beach are closed to cars on Sunday.
Going from west to east, you can join cariocas as they take their babies to the beach or play volleyball in Leblon, take a walk in Ipanema and do a little souvenir shopping at the Ipanema Fair (a couple of blocks from the beach), see the view from Arpoador and visit the Copacabana Fort.
Have lunch at one of the beachfront restaurants in Copacabana and linger on. One of the best budget programs in Rio is Copacabana on a Sunday afternoon. You can rent a bike - some fit the whole family, but only one pedals - buy souvenirs from street vendors, and have a snack at one of the Copacabana kiosks as a great way to close your weekend in Rio.