Headed to Portland in early August. Looking to head down to the Williamette Valley and spend a Saturday visiting wineries with my wife. Looking for a suggested tour vendor or list of wineries to visit on my own. We will have a car so can travel ourselves, but also open to a tour leaving from downtown Portland.
I don't think you need to do a tour. If you have a car, you'll enjoy the countryside much more and can change your plans if you see something interesting.
There are more wineries than you'll have time for, so check out a wine map like the one here and plot your course.
I like the stretch of Hwy 99 SW of Portland that heads towards the Oregon Coast. Between Newberg and McMinnville, there are over 100 wineries.
Anne Amie Vineyards is one of my favorites. Ponzi Wine Bar has a great tasting room with tasting trays of fruit, nuts, and cheeses to accompany the wines. If you like bubbly things, do a tasting at Argyle Winery.
Just start driving, pick out a couple "must try" wineries, then follow the roads and signs to others. You'll see tons of them.
The Willamette Valley wines website has maps and lets you sort by wine type, so if there's a specific one that you like, you can tailor your tasting that way. The region is particularly known for its pinot noir, but others are good too.
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I highly advise checking out Hawks View Cellars in Sherwood. Fantastic wine that retails for double zeros all over the world, and the winemaker AJ kemp has a fantastic Pinot selection, best in oregon. and he'll take you barrel tasting out of his finest if you tell him Justin Hopkins sent you ;)
True blue winemakers doing it for the love of the craft. Also, Dundee is a little hidden gem of great local whites...
Enjoy the view from up top the hills ;)