You'll enjoy the beaches and museums in Pelotas Centro. You might want to make time for a stop at Seventh of April Theater or Moura Pharmaceutical Museum.
If you're spending some time in Laranjal, Praia do Laranjal and Balneário Valverde are top sights worth seeing.
Três Vendas might not have many top sights, but Museum of the Baroness and Cathedral of Sao Francisco de Paula are two attractions nearby that you can check out.
You'll enjoy the museums and historic sites in Areal. You might want to make time for a stop at Museum of the Baroness or Charqueada Sao Joao Museum.
You might consider checking out CTG Cel Thomas Luiz Osorio Museum while you're exploring Barragem and the larger Pelotas area.