We had lots of fun with our family of four on Marc's boat.
The location is amazing, there are lots of top museums and activities at walking distance and we loved enjoying breakfast or dinner with a view from the deck of the boat.
It is a lot more fun than a regular hotel. We did this with young kids (2 and 5) but I am sure it would also greatly serve for a romantic weekend in Paris.
The rocking of the boat at night is great for falling asleep.