I really liked The Final Crossing by Harvey Ardman and The Magic Ship by Sandra Paretti. And Leviathan although entirely fictional is the best read. It draws heavily from the superliners Queen Mary and Normandie.
Four other items: 3 Related to Dame Agatha Christie:
1. In her short story set, "Partners in Crime" (featuring the husband and wife crime solvers Tommy and Tuppence Beresford), published in 1929, there is one story that mentions a trans-Atlantic voyage of the NOMADIC; figured Agatha drew on the names of the White Star vessels, including the Cherbourg tender; especially as
2. In her previous short story set, (Hercule) "Poirot Investigates", published in 1924, a story called 'The $1,000,000 Bond Robbery' deals with a shipment of bonds that disappears from the cargo of the ship OLYMPIA, on a journey to New York. The mystery is solved when it is learned the shipment was on the faster liner called the GIGANTIC.
I knew that Agatha must drawn on her knowledge of ships, and knew that GIGANTIC was the original name for BRITANNIC, and that OLYMPIA is borrowed from OLYMPIC.
3. In "Death on the Nile", the character of Andrew Pennington states that he sailed over from the States aboard the CARMANIA. However, Hercule Poirot later learned that he, instead, came over on the NORMANDIE, and it is noted that, with the NORMANDIE being one of the fastest ships of the time, that voyage allowed him to arrive sooner, in Europe, then Egypt, i.e. "You did not just have a 'chance meeting' with '(name of the eventual victim)'".
4. An espionage novel called "THE QE2 IS MISSING", written by Harry Harrison, and published in April 1982, deals with the QE2, during a round-the-World trip.
A friend of mine, who lives in Arlington (VA), lent "THE QE2 IS MISSING" to me, as we had both sailed on the QE2, including our last voyages in 2008.
I should be finished with the book this weekend; will see if my friend will allow me to lend it to a mutual friend in Toronto, who also sailed on the QE2, in 2002.
Joseph L'Episcopo's two books, "One Final Voyage" and "Oceanic Crossing" are both pretty good and available from Lulu either as downloads or as hard copy books. They're both alternate history books dealing with the White Star Line in the mid-1930's. OFV is about Titanic's final trip before her retirement and Oceanic III's maiden voyage as well as the start of a trans-Atlantic air service by White Star. OC expands on the air service, with some international intrigue mixed in and parts are set on Oceanic III and her sister Homeric, still fitting out in Belfast.