Besides the who dunnit plot, it depicts gay life in the 60's. Forster, E.M. Maurice. Character Alex Delaware has a best friend who's a gay LAPD detective named Milo. Milo's significant other is also a wonderfully sympathetic character named Rick who's an M.D. Lackey, Mercedes. Mage Winds and Mage Storms trilogies have gay characters.
Main characters are gay men but sexual matters are treated very tactfully.
In Savannah Reid series, main character is close friends with a gay couple Quinn, Eric Shaw. Dancing on Tisha b'Av. A Boy's Own Story. The Beautiful Room is Empty. A Farewell Symphony.