I’ve disregarded proximity and fashion. The recommendations below come from countless trips to Paris (sometimes for work, others for pleasure - I used to go there a lot). Now I’ll go at most 3 times a year.
I’ve been known to take day trips there just to buy groceries. And I’ve made a routine to take a detour during our annual trip to the Alps just for the sake of having a meal at Le Train Bleu (which is a notorious tourist trap, but oh so beautiful to look at).
So here we go. Looks like your trip is short, so is this list.
La Fontaine de Mars - this is as traditional as it gets. When Barrack Obama had time off for one meal while in Paris, he chose to go there. I’ve been going to this place well before him, the trendsetter I am.
Brasserie Floderer - one of the last family owned brasseries in Paris. This one has been in the hands of an Alsatian family since it started in the early 20th century. The steak tartare is prepared table-side, as it should.