If ever I was going to be embarrassed by reading a "type" of book, it would be the Regency romances written by Georgette Heyer. They are sold in the romance section and usually feature couples in period clothing on the cover.
However, nothing could be farther from the usual "romance novel" stereotype than these books. The closest analogy I can think of is Jane Austen; specifically Pride and Prejudice. Heyer's books are well researched enough to make you think that she was a contemporary and full of the sort of intelligence and humor that make you laugh out loud. Thinking over her books it is amazing how she consistently covered a wide range of characters and plots that included romance, fashion, upper classes, cross-dressing, arranged marriages, murder, intrigue, cant language, sarcasm, and humor. She also wrote a few mysteries but I never really enjoyed them the way I did the others.
Some of her romances are currently being republished, many can be found in second-hand bookstores, and most libraries have a wide selection as Heyer was amazingly prolific. A few of my favorites are The Grand Sophy, Venetia, Sylvester, or The Wicked Uncle, and The Foundling. If you haven't tried a Georgette Heyer book, pick one up, hide the cover, and prepare for a delightful and clever read.
UPDATE: I can't believe I forgot to mention that the grand finale of these books is usually when the heroine and hero finally ... wait for it ... KISS. Not quite the usual stuff we get given in romance novels these days. Not only intelligence, but respect of the characters.