Want an authentic Parisian brasserie experience? Try Bofinger. It's one of the classic Parisian restaurants that ends up in tourist guides much like Benoit or Le Petit Zinc. And like those places it delivers a very nice meal with good service, a comfortable room, and good food. They're all a bit overpriced and feel a bit corporate, but they're also quite good and reliable. Perfect for a first week in Paris.
Bofinger has an emphasis on fish as well as a fair number of Alsatian things on the menu. My oysters were absolutely lovely as was Ken's grilled sole. Really everything was quite good except for the tarte tatin, the russian roulette of French desserts (unless it's absolutely fresh, there's no point). Next time I'll order the café gourmand, a collection of tiny desserts with a coffee.
If you want to go for dinner you definitely need to make a reservation, preferably several days in advance. You want to sit downstairs in the beautiful room with the skylight, although how that works with non-smoking I'm not sure. I should note their telephone reservationist is very difficult; Ken and I have failed several times to communicate with them. They have an online reservation form that may be of some use for that problem.