There are a couple of tasting opportunities in the immediate Yakima area. One is Wilridge Winery, which overlooks Cowiche Canyon. Others include downtown wineries like Gilbert Cellers and Kana Winery. If you want to take a short drive to the lower valley, there are excellent choices a mere 30 minutes away. In Zillah I recommend Cultura Winery (fantastic reds, small quantities, not to be missed), Two Mountain Winery, and Bonair Winery (for fun tastings).

As for staying on Sunday night, there is a brand new Holiday Inn Express downtown, or a relatively new Hilton, both within walking distance to some nice restaurants with good wine lists, such as Tony's Steakhouse and Santiago's. Or, for some really good bar food, try the historic Sportscenter. 5 North just opened as well to rave reviews (but is said to be very spendy).

If you have any questions, feel free to message me. I live in Yakima.