I second Pablo - Puzzo is simply classics - I'm not tired of reading him again which is quite rare with books nowadays...
"For mafia, Mario Puzo is the master.
The Godfather
The Sicilian
The Last Don
Omertá
I am surprised nobody mencioned him already - maybe everybody is taking him for granted...."
also, I am a huge Harlan Coben fan - I've read all of his books and have for the most part LOVED them. They can catch you right from the first page, especially Myron Bolitar series.