I'm too tech-lazy, but whenever someone starts a thread, add that Alcantara, a short boat ride from central Sao Luiz, is a colonial time capsule that hasn't been touristified yet but will surely be turned into an Olinda or Ouro Preto. Try to be in Sao Luiz for their Bumba Meu Boi festival, while Alcantara has its own festas juninas around the same time - Brazil has so much more in addition to carnaval. The southern Brazilians, though, look down upon the Caribbean poverty of the north, and much of colonial Sao Luiz is in need of restoration, so don't expect a glitzy St. Barths.
The lencois are beautiful. They basically mean climbing up and down a lot of little hills so be ready.
From the picture on Google Maps, that must be the same sauna I went to in 2011. It was dead then, kind of surprising during festival time, though I did have fun with a scruffy surfer. Glad to hear it's lively now.