Scenery, history, culture, food and wine!
We had never been to this part of the US and this cruise was the perfect introduction. Second, part of the appeal was the small size of the ship (we only had 56 passengers on our cruise), lack of cell service or Wi-Fi for much of the time, no children and a complete absence of Disnification.
The cruise experience is based on comfort, good food, excellent service and cultural experiences. The highlight was a full day excursion into Hells Canyon on the Snake River in small jet boats that took us through whitewater rapids with ease; the boat captains were extremely knowledgeable about the history, geology and wild life of the area, and we got to see a herd of big horn sheep on the return trip. Other excursions included museums, national parks, and wine tastings. The entire trip was steeped in the history of Lewis and Clark, and the Corps of Discovery who travelled these rivers in both directions. We got to travel through locks, visit Bonneville dam and learn about the process by which the rivers were "tamed" for navigation while protecting the salmon migration, plus we saw a full lunar eclipse (although this was not a part of the published itinerary!).
This is one of the smaller cabin categories, but was perfectly big enough for the amount of time we spent in it (mostly sleeping!). We picked #311 specifically for a fixed Queen-size bed. The bed base is cleverly designed with luggage storage space and additional sets of drawers, and provides a lot of space for clothes. Two small complaints - there is no bed-side table on one side of the bed, and no electric outlet convenient to the mirror for hair drying etc.