Almost anything by Robert Heinlein - some of the best that jump to mind are:
Time Enough For Love
To Sail Beyond the Sunset
The Past Through Tomorrow
Sure, Stranger in a Strange Land is powerful and fun, but not nearly as epic and compelling as the bulk of his Future History “Lazarus Long” series.
Oh, but “Number of the Beast” gets a bit tiresome, IMHO - but that’s the only one that I’ve not re-read 5 or 6 times over the past 10 years.
I’d recommend Tyrant lo Blanc, the 15th century Catalan classic, sometimes called the first novel in the modern sense. Not translated till the 1980’s.
Moby Dick. Sometimes there’s a good reason books are required reading.
Check out Little, Big by John Crowley.
I find I get into an author’s work, and follow them faithfully.
I have never gone wrong with these authors:
Sharon Kay Penman: Very well-researched historical novels. It seems like she’s trying to put the reader eye-to-eye with the events.
Diana Gabaldon: A happy little romp through eighteenth century Scotland, Caribbean, and North Carolina.
Guy Gavriel Kay, especially the trilogy The Fionavar Tapestry**. Classified sci-fi fantasy, but a really good look at human attitudes at the same time.
Wilbur Smith: Just fun. Eighteenth-century fun set against how many different landscapes?
Jack Whyte: A re-telling of the Arthurian Legend, which sort of looks at the end of the Roman Empire, too, at the beginning of the series.
Oh, yeah, try"
Master and Commander
by Patrick O’Brian
Not long, but then if you really like it there are the other twelve books in the series. This is the first one, which begins the tale of Captain James Aubrey, and the Royal Navy.
Very good action books, soon to be hacked up into a movie. In the books you will find out what the phrase “by and large” actually meant, when it entered the language.
Bad romance though, if you need such things in an adventure.
Tris