Pretty much anyplace north of the river is reasonably nice, and the metro is super easy to use. Well, they don't have a lot of elevators and escalators, so it can be a bit of a problem if you have mobility issues or a baby in a stroller, but other than that it is rather convenient. The stops are closer together than in London and it will be easy to spot the best places to get off for tourist stops, because of all the other Americans getting off there! Well, that's how it was in June, anyway. I hadn't seen so many Americans in one place since the last time I was home.
We've stayed in Ibis hotels near Gare du Nord and Opera, and a cheap hotel in Montparnasse. The hotel wasn't anything special but there were excellent creperies next door, so we had a good time gorging ourselves on crepes and Breton cider.
