Shannara Series by Terry Brooks.
http://www.terrybrooks.net/bio.html
This is epic fantasy (14 books) with LoTR overtones but set in a post apocalyptic world where magic has replaced technology. The first book that was written, The Sword of Shannara, follows Shea Olmsford in his quest to recover the magical sword and use it to defeat the evil Warlock Lord. When this book was first published it rocketed up the best sellers lists, and with good reason. This is high fantasy at its best and a must read for anyone who loved Lord of the Rings.
Dragon Riders of Pern by Anne Mcaffery
http://www.iblist.com/series130.htm
Anne Mcaffery is one of those authors whose books just leave you feeling good once you read the last page. While a combination of Sci-fi and Fantasy (the argument continues about which one it is) they sit on my fantasy shelf. Anyone who has ever dreamed of riding a dragon should read these.
Valdemar series by Mercedes Lackey
http://www.mercedeslackey.com/biblio_series.html
This is a large collection and every book in it is excellent. The concept of being *chosen* by a companion, which is essentially a telepathic horse with amazing powers, is delightful. Once chosen you become one of the elite heralds, protectors of the realm. Start with Arrows of the Queen.
The Belgariad (5), The Malloreon(5), The Elenium (3), The Tamuli(3) by David and Leigh Eddings
http://www.eddingschronicles.com/index.html
I can't say enough good about these books. They are full of rich content, fantastic worldbuilding and plenty of sorcery. One of my biggest draws is the humor, the interaction between characters can be side splitting at times. They are rift with dry wit, affectionate banter and personal quirks. My favorite books hands down.
Riftwar Saga by Raymond Feist. Start with
Magician: Apprentice and Magician: Master
http://en.wikipedia.org/wiki/Raymond_E._Feist
Pug, an orphan boy is apprenticed to a magician and begins a set of adventures with his friend Thomas as their world is invaded by aliens who enter through a portal. These books were originally created as an alternate D&D world and quickly grew in popularity causing him to write a lot more books to add to the series.
Forgotten Realms books by R. A. Salvatore
http://en.wikipedia.org/wiki/Forgotten_Realms
There is no easy way to summarize these books, the scope is just too large. Best I can do is say they are full of adventure, elves, magic, and alternate worlds. Once you start reading these you will find yourself hooked.
The Wheel of Time (11 in print, 12th book to be written by Brandon Sanderson) by Robert Jordan
http://en.wikipedia.org/wiki/The_Wheel_of_Time
This huge sage takes place in a medievil type world where magic is called the One Power and can only be used by women. Men who are born with this ability are fated to go insane, if they live that long as once found are usually killed first. The saga centers around one man who, born with the One Power, is fated to save the world, while trying to save himself from insanity. The first book takes off slow as the extensive worldbuilding begins to take shape but once you get past that part you will never regret it.
A Song of Ice and Fire Series (4 in print, 3 planned) by George R. R. Martin
http://en.wikipedia.org/wiki/A_Song_of_Ice_and_Fire
A ruthless story about a ruthless world where harsh winterlike conditions make for harsh and gritty characters. This series has all the typical elements of sword and sorcery; wars, prophecy, dragons (later in the series), invading creatures from another land, treason, betrayal, love, death and loyality. Martin tells this tale from the viewpoint of many different characters, each bringing a unique perspective on the unforgiving land in which they live. This series is rift with sex and violence and I do not recommend for younger teens.
Kushiel Series by Jacqueline Carey
http://www.amazon.com/Kushiels-Dart-Jacqueline-Carey/dp/0765342987
If you want something completely different but with a definite adult theme try these. I recommend them highly for open minded adults. The world centers on a religion that honors sex and love in all its forms from sensual to masochistic. But its not a trash novel, the subject matter is handled in a very mature and reverent way. The story follows Phèdre as first a child in the "Night Court" to her training as a spy and on to her adventures both at home and across the lands. There is a touching love story, high adventure, political intrigue, and a complex world to enjoy. This series is on my favorites list.
The Sword of Truth, written by Terry Goodkind
http://en.wikipedia.org/wiki/The_Sword_of_Truth
Set in a medieval type world, Richard Cypher, a woods guide, lends a hand to a stranger who is searching for a nameless Wizard who disappeared many years ago. Along the way Richard is challenged in every way possible, physically, mentally and emotionally. This series showcases the virtue of remaining true to yourself and your morals, regardless of what life throws at you. The author himself says he wrote this series with adults in mind because of the focus on philosophical themes