The Dark Tower series by Stephen King is my all time favourite series. I just finished the Dune trilogy, which was awesome. I am currently reading Name of the Wind by Patrick Rothfuss, and am enjoying the shit out of it.
If you're into fantasy, then check out the entire "Cosmere" collection of books by Brandon Sanderson. They are page turners to say the least. Especially the "Stormlight Archive".
I am also a sucker for the His Dark Materials series. But I could understand why an adult may have a hard time getting into them. They are high fantasy aimed at teens/ young adults, but have a very grown up plot if you are able to read between the lines a bit.
I love talking books, so I'll reply again if I think of anything else worth mentioning.