I have, three couples in a large 3-bedroom boat on the Canal du Midi.
We picked a boat up in Marmande and sailed to Condom via Agen. It was very pleasant – I’m sure we’ll do something like it again sometime. It’s not an activity holiday, you just potter about for a week. If you’re the kind of person who needs to be doing something you might get frustrated. And the weather makes it or breaks it – obviously the chances of good weather are high in the south of France but if it’s raining it wouldn’t be much fun.
We bought wine, cheese, fruit pate etc and had lunch on the boat in the sun. Evening meals were wherever we turned up – not all excellent to be fair as some of the stops were in tiny out of the way places. Rural France is boring for vegetarians.