If you fly fish, the Yakima has been fishing real well lately from the canyon all the way to Cle Elum. There is O.K. fishing below Roza Dam if you are not a fly fisher. Also, most all the lakes around E-burg fish pretty well with some nice fish in them. Some have some good cats in them also. Drive a little farther east and Lenice, Nunnally, and even farther Rocky Ford are great at times, although Aug. is a bit warm for Lenice and Nunnally.
Don't shorchange the rodeo though....it can be an blast, the city is usually one big party.
If you are a fan of great beer you have to go to Grant's Pub while in Yakima....some say it started the micro beer craze, and the brew is fantastic!