Hello! Just signed up so I could contribute to this awesome thread.
I would like to recommend the Vlad Taltos series by Steven Brust. They're a mix of fantasy and detective genres with a good amount of action set in a well built world. The books are (mostly) set in the Dragaera (Dragaerans = elves, but call themselves human, and are the dominant species of the world) capitol city Adrilankha where the Easterner (actual humans, but are looked down upon as barbarians and lesser beings by the ruling class and are regulated mostly to the city slums) Vlad goes about his day working as an assassin, gangster, and part time thief. With that said, these books are NOT high fantasy. More like fantasy-lite with noir and humor.
I don't believe they ever got very popular, but I still remember sneaking out of a very boring sunday school class as a kid, going across the street to the local library, and finding the book Dragon (hey, it had a cool cover art and said DRAGON). This series is actually what got me into fantasy novels.
Also, 100% in agreement with Babybalrog. Dune is, and probably always will be, my #1 go-to book.
