Houseboat on the Seine?

Worst idea I've ever heard.

Noise? Imagine how much noise the diesel engines on all those tour boats make as they go by every ten minutes -- and the wake they kick up. They'll quit by ten pm or so; then you'll be able to hear the noise from the Voie Pompidou which goes on all night.

Playgrounds? Beats me. Can't picture anything except the merry-go-round in the Tuileries.

Groceries? Sure. There are little high-priced QuickStop type stores all over the place. Nothing really good to buy. The closest shopping steet I can think of with decent produce and fresh meat and such is close to Les Halles -- that's only a mile and a half.

Metro? The closest station is Tuileries, just across the way. Bad thing with this is that to go west (where there isn't too much on your side of the river) you have to do a bit of tunnel-hiking with the kids at Concorde. Going east, you have to make all your changes at Chatalet/Les Halles; this is a real delight since it has the worst tunnel complex in the city (up and down, some tracks a half-mile apart).

Art museums? How much time are the kids going to spend in those? Probably not much since the notion of playgrounds exists.

Save the houseboat splurge for Amsterdam where it's really worthwhile.

.....this from somebody who lived on his own boat for a few years and really liked it.

Another thought:

Those metal pie pan looking things on the dock lines between the boat and the shore bollards on the are called rat guards.

Walk the lower quai one night. As you pass under a bridge turn a flashlight up into the corner (sort of where you'd picture a bum would sleep). Keep walking; they won't jump on you. Besides, you just passed under some more that were looking at you from the bridge stucture over your head.