Woodinville is a good place to try a number of wines in a small area. Yes the wines are made from grapes from Eastern Washington and some of the Woodinville wineries may have tasting facilities over there also. There is an area south of Woodinville on Hwy 202 and the roundabout at NE 145th where a number of tasting rooms are. If you're driving a long rig you may have a difficult time getting around and finding a parking spot. You can walk to 20 or more tasting rooms in that one area. The Chateau St Michelle and Columbia winery are just west of there on 202 along with Red Hook Brewery and Woodinville Whiskey. There are a couple of good places to eat such as the Purple Cafe and the Barking Frog. You might want to narrow your choices down by focusing on the wines you like the most and what wineries produce them. I like the Italian types such as Barberra and Sangiovese as well as a Zinfandel. That usually narrows things down a lot and I can add a couple from places nearby. Not sure you'd want to tackle Seattle traffic after that so the recommendation of Lake Pleasant RV Park would be a great choice.
Doug