Not an expert on the site yet, but majority of the rooms with a shorter walk are the Ipanema Tower, accessed from a central bank of elevators (Ipanema Elevators). The three-winged tower rises above with the elevator at its core.
Here's a link to the map:
http://www.riolasvegas.com/images/non_image_assets/Rio_CasinoFloorPlan_4cKO.pdf
and the satellite image that you can correlate it to:
http://mapq.st/1b2iGlt
Just key on the pool (water type, that is) layout to compare the two.
The current plan has all the tournament tables in the Rio Pavilion, Amazon Room and Brasilia Room. A few action tables will be in the Miranda Room.
The Masquerade tower will be a longer walk, and goes through the casino.
Buddy