If it's possible to not love Billy Wilder, I don't know how. There's an infectious joy running through his movies, even when the subject matter gets dark.
Which it doesn't in Love in the Afternoon. It's a sprightly romantic comedy where the sexual innuendo is pretty single-entendre. But that's okay. It's not as gloriously wacky as Some Like It Hot, and it doesn't have the heart of The Apartment, but those two are among my all-time favorite films, and a high standard to match. It has a lot of great jokes, and gives them a good summary in its last act.
The trailer below isn't that great. I'm starting to think trailers that managed to sell the movie without giving away the entire plot have always been the exception. But it does have a glimpse of the sauna scene, complete with gypsy musicians. That's one you have to see.