Madame Bovary, by Gustave Flaubert. There are many translations available... we've ordered the Francis Steegmuller (scholar of French lit & late husband of novelist Shirley Hazzard; excerpt is here) and the B&N edition (introductory note is here), and several in French, for the purists. You'll find them in the Staff Recs section and upstairs in Fiction.
You can compare different translations online or at the store or library; there won't be much difference, especially with Flaubert. Later editions may have a more "modern" feel to the vocabulary & sentence flow. Here's a free full study guide.
(PUT TOGETHER BY HARVARD STUDENTS... IT HAS A LOT OF INFORMATION, AND THE MAJOR THEMES SECTION RAISES SOME INTERESTING POINTS.)
ESSAY BY JOYCE CAROL OATES AND A DISCUSSION.
MORE INFORMATION AND SOME INTERSTING TOPICS.
ARTICLE BY A.S. BYATT USES A LOT OF FRENCH QUOTES, BUT THERE'S ALSO SOMETHING FOR THOSE OF US WHO CAN'T READ THEM.
ONE ARTICLE I READ SAID FLAUBERT WAS UNTRANSLATABLE, AND CAN ONLY BE UNDERSTOOD PROPERLY BY THOSE WHO HAVE FRENCH AS THEIR NATIVE LANGUAGE. WE'LL SEE ABOUT THAT!