Exactly how steamy is this story?
PG-13
Yes, there's adultery in this book. And yes, there's a lot of flirting. And a sexy pin-up girl dream fairy.
But when he published this book in 1922, Lewis didn't want to give the public any easy reason for ignoring his satire of the typical American businessman. Had he been steamier in his writing, average people could have written him off as "vulgar" and paid no attention to his book. As it stands, though, there's never really any mention of sex in this book, only stuff (like smooching) that tends to revolve around sex.
Even Babbitt's affair with Tanis Judique is something you need to assume because of the fact that he spends nights at her apartment. The book never comes out and says they do the deed. But sexual desire and frustration is everywhere in this book, just never directly addressed.