A while back I went on a ride with Team RWB out on River Road. It was a great ride of 35 miles with about 1300 ft of climbing. It took us on River Road which is always nice when there’s little traffic, and it also went on some easy rollers up by the dam. The thing about River Road is that during the summer it has very heavy traffic so it’s best to avoid it. The rest of the year, however, it’s great.
Another thing to keep in mind is that if you need some climbing there are plenty of nice rollers in the area. Most of the highways have good shoulders too and if you know where to go, the quiet roads are really nice. You can click on the Strave link above if you want to see the route. Have fun out there!