I enjoyed the HP books- though in my opinion Books 1-4 were great, but 5,6 & 7 bar the last few chapters weren't as exciting or interesting- Still they're one book series that I've read almost annually since I read the first one. I think like LotR they've become one of those books that you
have to have read- whether you really like it or not in the end. And the films do the books no justice
I second Smaug for
A Song of Ice and Fire, though it is a much more grown up type of fantasy that Inheritance.
The Same goes for Gregory Maguire's Oz books-
Wicked- The Untold Story of the Witches of Oz,
Son of a Witch and
A Lion Among Men, which are amazing too
Wicked is actually much better than the stage version. He's really good at telling a well known story from the PoV of the Bad Guy
But if you prefer something more 'fairytale-esque' Gail Carson Levine's
Ella Enchanted and
Fairest are lots of fun.
I can also recommend Tolkein's:
The Children of Hurin- it's one of the stories included in the Silmarillion but in more detail. If you're finding the Silm tough, CoH is a good way to ease yourself into the high drama of the first age- and the pictures are beautiful!