I’m sorry that I’m just now looking at your post and you’re probably already in Paris! Hopefully you will check in here because we can all continue trying to help you in narrowing down your choices in Paris.
A couple of thoughts: First, I second Simplydg’s suggestion of La Coupole which is a classic and beautiful art deco brasserie where you can find many traditional French dishes. I think I slightly prefer La Rotonde also on blvd. du Montparnasse, but they are both superb. Second, you might consider Chez Monsieur right across the river from you - also serving classic French cuisine. And Simplydg also mentioned Le Bon Georges in the 9th, which is great especially if you order their beef tartare or a steak, but be sure they don’t overcook it which many Parisian chefs think is the way American’s like it. My husband always asks for his steak “saignant” (medium rare), while I request “bleu” (rare).
