Make sure you go to a bakery dedicated to bread, and only bread. Forget the food markets where bread may have been sitting on the shelf for a few hours. Go to a place where each loaf of bread has pointed ends, a tell tale sign that it has been hand made. Rounded ends typically means it was machine made, so try to avoid those. The bread should have a crispy hard exterior with an airy fluffy interior. Squeeze the loaf to make sure it's warm and fresh before your purchase. By the time you finish your inspection of the bread you will look like an anal Parisian or a psychotic tourist.
With a crazed look in my eyes and my mouth watering, I inspected the bread at Eric Kayser. This was where I found the best bread in Paris. For €1.10 I was able to buy a whole baguette, and shamelessly eat it on street immediately after purchase. Nothing from New York compares. With multiple locations in Paris, you are bound to stroll upon one of the Eric Kayser locations during your travels. And when you do, I beg you to indulge!
F your diet and eat the baguette on the spot. Do not use portion control, eat it whole because you can taste the culture of Paris when it is that fresh! Eat it right away and worry later! There's always ex-lax and water to wash away that post-vacation bloat when you get home. There is a national campaign in France promoting baguettes by reminding citizens they are a good source of protein and fiber and a vital part of a healthy diet. Though the fact is the French are eating half the bread that they did 50 years ago, it still remains a staple of their daily diet. Do you see any fat French people? I don't. All the more reason to indulge!