Reddit has a large number of communities or subreddits that focus on books, some of which are very specific and delve in subgenres that you may have never thought about. It can be a great way to find read alikes or to satisfy a patron who has very distinct tastes. You can also use ideas in the threads and posts there to launch a book display as well.
Enter in a genre and search for communities. If you search for romance book, you will see the following communities:
Romance Books
Spicy Romance Books
Contemporary Romance
Dark Romance
Romance Authors
Historical Romance
Fantasy Romance
Free Romance Books
MM Romance Books
Romance for Men
Queer Romance Lit
Wholesome Romance
Science Fiction Romance
Romantasy
Paranormal Romance
Sapphic Lit
Romance Anime Manga
Romance Anime
Reverse Harem
Mafia Romance Books
There are likely even more...
Search for a read alike and you will find readers who have posted their suggestions. I looked for read alikes for Sarah MacLean and found many posts with suggestions. While you might not agree with all of them, they can provide the start of a conversation as well as options for a book display.
You can search Reddit without logging in which is helpful. Even the threads about books people dislike can help you out if they provide reasons why. Someone's hate read is someone else's catnip.
It's a useful site to keep in your list of tools you have for passive and active readers advisory.