We went in April this year and enjoy the Bistro du Breteuil in the 7th. It and the Canton in 6th (yes, there is good Chinese in Paris!! and they are open on Monday and be sure to have a soup) are the only restaurants we have gone to on every visit. But, we will add l'Avant Gout to that list. There is a great, but tight, Italian place on Mabillon right across from the market in the 6th, which is open on Sunday evening and has great pizza and pastas. These are all about Eu35 places.
Two of my absolute favourites, which we visit over and over, are: Au Boeuf Couronne, 188 av. Jean-Jaures, La Villette (still Paris, on the Metro, but a bit further out). Beautiful old-fashioned restaurant, where families of three generations go for Sunday lunch (my recommended meal there--book a table!) and your waiter/ress does everything from carve your chateaubriand to flame your crepes suzettes. You feel 100% Parisian, not touristy at all. Please go!
Also, very central, near the Louvre, Le Dauphin, 167 rue St. Honore. It's a classy, yet small and comfortable, place specialising in Southwestern French cuisine. We went the first time as the reviews in the window indicated it's the place where all the up-and-coming chefs in town go on their nights off. And it is great! Things are different enough to make choosing hard, but not so much that you end up disappointed. I can still rememeber every single dish I've had there!
I second the recommendation of Patricia Well's "A Food Lover's Guide to Paris". If you have trouble finding a copy, go to www.abebooks.com (They can locate a used one for you.) As to having a car in Paris, there is absolutely no chance you will find a parking spot in just one week....
There are so many great places to eat well and for value in Paris. Some places are closed in July, so I recommend picking up Patrica Wells' Food Lover's Guide to Paris. I've tried about a dozen places from the 4th ed. and have not been disappointed yet. My favorite moderately priced places:
Le Fountain de Mars
Brasserie St. Louis
and my fav: Chez Denise