A friend cruised on a Viking ship in August and had a bad experience. The majority of the crew did not speak English. They did not have a full bathroom, but rather the shower was a hose that came out of the very small sink.
We did a Rhine River cruise this past year on Uniworld and will do a Danube cruise next summer. I highly recommend Uniworld. They do a Russian river cruise too. Full bathrooms and full English speaking crew.