Here is a view of the Viking Spirit, our floating hotel for 7 days. It holds about 140 passengers, has a dining room on one end, a lounge on the other, and cabins in the middle. There is a sun deck up top, not that it is getting much use on this trip.
What we enjoy most about river boats is that their size allows them to dock right in the middle of the towns we visit, so no time is wasted getting to see the cities along the river.
We are truly treating it as a hotel, since we most like to travel independently. We are skipping the walking tours in most cities in favor of doing our own, using guidebooks or tours from the TI office. And if all goes to plan, we will only have eaten dinner on the ship the first night, as we are taking advantage of the schedule of being docked each night and, well, being in France where the food is amazing.