Again, UW's size is the defining factor here. If you're looking for hot guys and girls, they are definitely to be found on campus, and many believe they are concentrated in the Greek population. Likewise, if you're attracted to athletes, hippies, stoners, skaters, ravers, whatever, UW pretty much has it all. The dating scene varies from group to group, but perhaps one trend is that underclassmen are more likely than upperclassmen to be single. Underclassmen are more likely to stay single and have casual hookups, whereas upperclassmen are more likely to be in a meaningful-or at the very least, exclusive-relationship. Toward the tail-end of college, a lot more people seem to pair off.
UW has a happy medium between the more materialistic Southern California brand of guys and girls and a more hippie, laid-back type that some of the schools in Eastern Washington tend to attract. You won't confuse campus for Hollywood or Malibu, but there are definitely plenty of attractive people of both sexes. And if you go to some parties, hang out at some popular places on campus, and maybe do some heavy lifting or jogging on the treadmill at the IMA, you're bound to run into them one way or another.