I thought you would love river cruising! The older I get the more I enjoy the river cruises. I have one booked now for next October from Romania to Hungary. I wish I had one sooner. You might want to try one of the Spring Tulip cruises. I did one in 2011 on AMAwaterways. The Kuekenhof Tulip gardens are beautiful. I ordered Tulip bulbs from them and they shipped them to me in the Fall for planting. This past April they all came up and looked gorgeous.
I don't miss the big entertainment at all on a river cruise. I love being able to walk right off the ship into the quaint towns. I love the old European architecture.