No matter which Paris avenue these gentlemen choose, they will definitely encounter a pastry shop. Chances are the pastries will be delicious. They may even decide they want to go to several pastry shops and compare; I know someone who did that.
I was particularly enchanted with French macarons, those crunchy, chewy meringue-based cookies with the various fillings. They have become popular in the United States now too, but I have yet to find a good one here, or at least any that compare in any way to the ones in France. In case you've never had one, macarons look like this. If you were just buying something based on appearance, you might never try one.
|Renard Gregory's chocolate macaron is the best.|
This is called an Ispahan, a magical creation that combines the flavors of rose and raspberry with litchi. One of them was from Ladurée and one was from Pierre Hermé. Although they were both excellent, one was better than the other. Unfortunately, I don't remember which.
Maybe it was the one from Pierre Herme. I suggest you try both!