We chose a cruise from Prague to Basel as we had never explored Eastern Europe. The trip started in Prague, but we didn't board the boat until Nuremburg.
Each day we visited one or two different sites. All the guides spoke excellent English, some were oriented towards history and art, others toward more touristy things like shopping, but all were engaging. There were about 70 on our boat, and the group usually split into three parts, one a slow group for folks with issues about walking.
The service on the River Ambassador was simply impeccable. And the food? To die for. I actually lost weight due to all the walking, but I could have gained five pounds.
The only negative is that the cabin was quite small. However, it was extremely clean (the staff tidied up twice each day), and of high quality design.