My travelling companion chose the date--cruising along the Seine in December.
Upside, France is wonderful anytime. We had cool weather but the decorations and the lack of the tons of tourists around during warmer weather made up for it, at least for me.
Moored alongside the quai within walking distance (15 min)of the Eiffel Tower was almost magical. It was great in the evening when the lights flashed on the Tower. Downside was that the metro took a fair bit of time to get into town. It is certainly doable but the metro station for the Quai de Grenelle did not have an elevator available. Also the one wicket closed for lunch so you needed change to buy a ticket from the machine during the clerk's lunch break.
Fairly close to the main entrance so if you forgot something you could easily go back to get it.
Bed beside the window was a little cool in December. We had the beds separated to there was lots of room to walk around the cabin.