Probably one of my favorite Regency romance books is A Lot Like a Lady by Kim Bowman and Kay Springsteen. It's a relatively new release (March 2012). They do such a good job with their characters and developing the relationship between them. The research that went into the story is evident too. Funny situations and humorous secondary characters. Love this one! Not gonna lie, I've read it more than once. Can't wait for the sequel to release!
Ladies’ maid, Juliet Baines has gotten herself into a pickle by agreeing to go to London and taking the place of her mistress and best friend, Annabella Price, stepsister to the Duke of Wyndham. After all, what does a servant know about being a lady? But Juliet soon finds that pretending to be a lady isn’t nearly as hard as guarding her heart against the folly of wanting a man who’s completely out of reach.
Graeme "Grey" Roland Dominick Markwythe, Sixth Duke of Wyndham, approaches his duties as a nobleman with great dedication and meticulous care. And he’s a man who is not easily fooled...except when he tries to convince himself he's not utterly and madly in love with the beautiful imposter who has turned his life upside down. Will society and his responsibilities to his noble status keep him from opening his heart to the woman he loves?