We were a couple, traveling on our own, and found it easy to make friends. The dining room setup encourages mixing. There seemed to be mostly Americans on board, with a smattering of Canadians and Aussies.
The itinerary worked for us since I was pining for another visit to Paris and my husband wanted to see the landing beaches. We did Paris on our own, staying at the delightful and perfectly-located Hotel Britannique. I think, however, that some of the other rivers may be more scenic for cruising. Plus, the trip to the beaches required long bus rides.
If we take another river cruise, I wouldn't even look at another line. AmaWaterways will be the one! And to drive home the point, not only did they provide a gift of a custom-designed scarf to every woman on board at the end of the trip, but a hand-written "thank you" postcard, signed by the captain, hotel manager and cruise director just arrived in my mailbox!