Pratchett is always a good choice. I've enjoyed Raymond Feist quite a lot, and he was my favorite author before I got my hands on Elantris and Mistborn. Start off with the Riftwar Saga (Magician, Master Magician, Darkness at Sethanon), and then just see what's next chronologically - there are quite a few books. The story might get a little repetitive after a while, but the language is beautiful enough to make up for it, I think. Language and characters. Oh, and cosmology. And a few other things I can't think of right now...
Another option would be Steven Eddings (sp?) and his Malazan Book of the Fallen. I've said it before, and I'll repeat - I think Brandon's style is somewhat dark, which is something I completely adore. Well, Eddings's style is horribly morbid at times. I think he is very much like Martin in some ways - killing his old characters off, because they are getting old, and then introducing new ones, and killing them too, because they are too new. Funstuff. If you do decide to go with Eddings, keep in mind that usually the first half of each book will look boring and alien, because all of this knowledge about the world is being dumped down on you, and there is very little explanation. And then the second half will make your jaw drop every second page.
And another option would be David Farland's Runelords. I really don't have a whole lot to say about them (because I rarely remember much of a book after I've read it only once), but they are good in pretty much every aspect of the fantasy literature.
