The Sunday Review/Journal has a brief history of the two groups in anticipation of the possible merger.

http://www.reviewjournal.com/lvrj_home/2004/Jun-06-Sun-2004/business/24044172.html

And there is a rumor now that Harrah's will add a third tower to the Rio rather than build a new mega resort on the strip.

Scan from the Rewiew/Journal

http://www.reviewjournal.com/lvrj_home/2004/Jun-06-Sun-2004/business/24022798.html