I'm not as widely read in fantasy as some others here, but if you want Wow! and mention Tolkien I would agree with the Raymond Feist Magician/Silverthorn/Darkness at Sethanon suggestion. I've largely gone off the author now. He didn't move on so I did instead - but those original three books were amazing.
I'd also put in a strong recommendation for the Feist/Wurts x of the Empire trilogy. I found it possibly even better than Feist's trilogy, although perhaps not as Tolkien-ish.
I'm a big big fan of Susan Cooper's Dark is Rising sequence. It's bloody marvellous and a pretty easy read as well. It's YA but as you've mentioned Harry Potter, that shouldn't be an issue.
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