Repost of a favorite from November 25, 2012 with a few additions:
The erotica I hold in the highest esteem is that of Anias Nin. You can Google her and find many writings, but she published two books of short stories that are my all-time favorites. They are subtly stimulating and make a classy gift for grown up tastes. The hardcover version is the one to give, but will have to be found used from one of the many book dealers Try Allibris or there are many to be found when putting in the title, through Barnes and Noble or Amazon). Just search for like-new condition, with the dust jacket.
Little Birds, on Amazon for $11 and Delta of Venus, also on Amazon for $11ish.
She also kept diaries that have been published in many forms, the most famous being Henry and June, which documents her torrid affair with writer Henry Miller. Drawn from the original, uncensored journals of Anais Nin, "Henry and June" is an intimate account of a woman's sexual awakening. It covers a single momentous year - from late 1931 to the end of 1932 - during Nin's life in Paris, when she met Henry Miller and his wife, June. She fell in love with June's beauty and Henry's writing and, soon after June's departure for New York, began a fiery affair with Henry, which liberated her sexually and morally but undermined her marriage and led her into psychoanalysis. One question dominated her thoughts: what would happen when June returned to Paris? That event took place in October 1932, leaving Nin trapped between two loves - Henry and June.
While this was new in 2012, and now it's been made into a movie, it's still notable. The book that was on everyone's lips (pun intended) was Fifty Shades of Gray. Someone on your list may want to read it just to know what everyone else is talking about. People diss it as "Mommy Porn," suggesting it's basically a bondage-flavored romance novel that's palatable enough for most tastes.... Everyone who has read it, from friends to Reviewers from the New York Times and NPR, say it's poorly written but there's something compelling about the story - SO compelling that perhaps you have to give the first at least, if not the whole trilogy. HERE it is on Amazon for only $9.
And then there's always the classic - Lady Chatterly's Lover. The Literature Network describes it well: Most famous because of its obscenity trial during the 1960's, Lady Chatterley's Lover is far from a "dirty book." Rather, through his usage of local vernacular and an in depth look at the true relationship between two humans, Lawrence has successfully portrayed sex as sacred in a world where sex is viewed as nothing more than physical pleasure. This novel is a masterful example of a writer going back to everyone's common roots and emerging with a thought provoking masterpiece designed to affect a change within its readers.
While we're on old classics, I must mention Nabakov's Lolita - Wikipedia says: The novel is notable for its controversial subject: the protagonist andunreliable narrator, middle-aged literature professor Humbert Humbert, is obsessed with the 12-year-old Dolores Haze, with whom he becomes sexually involved after he becomes her stepfather. His private nickname for Dolores is Lolita.
There is always The Story of O, by Pauline Reage, though this is really a very harsh one, in terms of the dom-submission theme towards the female character. Might be pushing it for the average person. I mention it because it's a classic.
Anne Rice put out a trilogy of erotic novels under a pen name of A. N. Roquelaure, before she rose to international fame with her Vampire series... It didn't do much for me but there are many tastes. THe titles are: The Claiming of Sleeping Beauty, Beauty's Punishment and Beauty's Release. They're BDSM novels set in a medieval fantasy world, natch, against the backdrop of the fairy tale of Sleeping Beauty.
How about a beautifully bound volume of Sappho, the Greek poetess from the island of Lesbos who wrote love poetry to young women? Or from one of my favorite writers, Yukio Mishima, whose homoerotic novels, Forbidden Colors and Confessions of a Mask are intriguing reads...
In addition to Sappho, if you're interested in more ancient erotic poetry here's a short list:
Ovid — Roman erotic poet
Catullus — Roman erotic poet
Sextus Propertius — Roman poet
Petrarch — Italian poet, considered, together with Dante, the father of Renaissance. His love sonnets dedicated to Laura are masterpieces of erotic poetry
Bai Juyi– Romantic poet of Tang dynasty
King Solomon–Author, according to Judeo-Christian tradition, of the Song of Songs.
John Wilmot, 2nd Earl of Rochester — British 17th Century libertine
There is a pretty comprehensive list of sex manuals, and erotic novels on Wikipedia, which you can find HERE. Happy Hunting...
TIP: While I've linked some of these books to Barnes and Noble or Amazon, it's worth Googling around to the many used booksellers to find a volume that suits you. Used hard covers with interesting dust jackets make wonderful gifts, in fact they can be extra-special. Most are available in e-versions, but especially for this genre, I think not as nice as it could be for a gift. But if you can only find paperbacks of the ancient poets... go for it. There's a romantic notion in that whole thing in itself.
AND PS: There are movie and audio versions of almost all of these if reading is not... and more.