The first LaSalles are noteworthy because their styling was directed by Harley Earl whose work so pleased GM's top management that he was given the opportunity to create a permanent styling group for the corporation, a first for the American automobile industry. Therefore, all future LaSalles (they were produced through the 1940 model year) were designed under Earl.
It happened that Earl cribbed a good deal of the first LaSalle's appearance from French Hispano-Suizas. Perhaps that was a factor in early LaSalle advertising that featured the cars in European -- especially French -- settings. The French angle provided some prestige to those "companions cars" to Cadillac, because French luxury cars were highly regarded in America during the 1920s, as was French culture.
Information about Wilson can be found here and, especially, here. The latter link includes the following quotation from Wilson, something of interest to historians of illustration art.
"What pulled me through the two wars and the well-known depression was my idle time in which I used to fiddle around with new methods of getting a drawing to reproduce as near facsimile as possible. You must remember that printing and photoengraving were rudimentary then compared to what they are today. Whatever style I may have now was brought about by striving to get my drawing printed as nearly as possible to the way I made it."
Toward the left is a woman in regional garb; near the right is a French army officer on the verge of falling over backward.
You can click on most of these images to enlarge. That will allow you to better see that the driver jauntily has a pipe in his mouth.
At the right, over the sea is the Jetée-Promenade de Nice, a landmark structure destroyed in 1944. The Promenade is still there, and often much more crowded than Wilson's illustration shows.
A fishing town. Nothing swanky like Nice's Promenade. But this also might be on the Riviera due to the mountains or very high hills in the background. On the other hand, the rest of the setting seems more like Brittany. Perhaps the background terrain was added for compositional purposes.
This is curious because one would think the setting is the Paris Opera (now the Opéra Garnier). But it isn't. Perhaps it's an opera house in another French city. Or maybe Wilson depicted an imaginary opera house. Knowledgeable readers might set us straight in comments.
For a change of pace, this is London near the location of the Bank of England. Once again, I cannot identify the building in the background when comparing it to Google street views (as I did researching the previous image). There is no record that Wilson was sent to Europe to seek backgrounds for the various advertisements, so he might have relied on photographs or used his imagination as inspired by photos.