I've been to Manaus, Brasilia, Belo Horizonte and Salvador recently. Always working (shooting 360° photography) and with never enough time to look around and enjoy a place as a tourist so I can't really say what the best destination for you is.
One place that comes to mind is Superclubs Breezes at Costa do Sauipe for the watersports. It's about an hour from Salvador which is a very interesting city. You could visit Salvador and see the highlights, eat Bahian food which is incredible and then spend a day or so at Breezes. It's just a typical all-inclusive but it might be easier than trying to do it on your own.
I was there less than 24 hours and only got in the ocean when it washed over my feet while taking a photo on the beach. Check around for more informed opinions it this interests you.
I'm adding a link to our website which has hotels throughout Brazil and a link to Breezes Sauipe activities.
Where ever you go, have fun.
Our website's digital brochures -- turn off pop-up blocker to view
Breezes-- Costa do Sauipe