I found it pretty hard to move around Brasilia, public transportation seemed pretty bad (we had a friend drive us around), but it's a nice city. I liked the lake and the Niemeyer church.
Been to Rio only once for work and the only touristy thing I did was Sugarloaf Mountain, the view is amazing. I had friends tell me that Corcovado is better, idk though. Here's some pics I took with my phone:
Everything was crazy expensive in Rio too btw.