Ray Bradbury, for a refreshing and original use of language...and for honing your imagination he can't be beat! Start with some of his many short story collections, preferably The Illustrated Man, S is for Space, and October Country...he is one of the masters of the short-story form (along with Somerset Maugham). His novels include Fahrenheit 451, The Martian Chronicles, The Halloween Tree, Dandelion Wine, and Something Wicked This Way Comes.
Herman Hesse -- Demian, Siddhartha, Steppenwolf
Alistair MacLean -- if you like gripping adventure/thrillers written in high literate style check out Ice Station Zebra, The Black Shrike (my favorite), The Guns of Navarone, Where Eagles Dare, Fear is the Key, The Satan Bug (the original biological outbreak story), and a host of others.
Edgar Allan Poe -- short stories of his such as The Cask of Amontillado, The Telltale Heart, and many others will leave you spellbound. And though macabre in theme, he uses a wonderfully elevated style of language to relate them. And don't miss his poetry either, works such as The Raven and Annabel Lee are a must!
Joseph Conrad -- luscious language! Conrad, who was born in the Ukraine, spoke Polish as his native tongue, and learned English as a second language, took his writing to brilliant heights. If you want to fall in love with the English language look no further than Conrad (well, okay, Shakespeare, too ;)): Lord Jim, The Heart of Darkness, Typhoon, many others.
Oh, and if you like history don't miss H.G. Wells' two-volume The Outline of History.
