Four come to mind. They are road tours but usually not on two many busy highways.

1. Cycle Oregon. I have done four. Extremely well supported, camping event (although sometimes there are hotel options for extra $). The route is announced in mid-February and registration opens then. Sometimes it sells out in an hour or two. It all depends on the route. If you don't like large crowds, it's not the event for you. There are usually about 2,000 people.

2. Adventure Cycling's Cycle Montana uses a very nice route in 2014. I have done portions of it during solo, unsupported tours. The day through the Grasshopper Valley and the Pioneer Mountains (Day 4) is very, very nice. So is Day 3 and the way out of Butte via Pipestone Pass (Day 7). Butte is an interesting place to walk around. I did an ACA tour a few years ago. It was well supported with a manageable group.

3. ACA's Cycle Washington. You want Cascades. It crosses the North Cascade Mountains. Stunning ride.

4. Timberline Adventures does a trip through Crater Lake N.P. Crater Lake. 'Nuff said. Another stunning ride. I have several friends who have done that trip and really liked it and the company. It's a hotel trip, so it's more expensive, but a relative bargain.