Sightseeing & trips in our region (Brasilia)

On our last Get-together, I was talking with Michael Donath and his wife Katia about things to do in and around Braslia. What is worth seeing and what is rather not what one expects. I imagine we are all always looking for things to do and see ... or things to show our friends when they come to visit... So I decided to open it up for discussion.

What are your favorite places in our region? What are your experiences? Any special tips you want to share?

Looking forward to your inputs.
Cheers
Petra