I'm right in the middle of Anathem, too.
I don't think there are too many fantasy elements and it's definitely not "medieval fantasy", but I love it. It could be described as Book Of The New Sun with scientists instead of torturers. Absolutely brilliant and I think Stephenson is one of the best writers today.
That's why I'd recommend the Baroque Cycle. Not fantasy and not medieval, but you can't get more epic than that and it's insanely interesting and entertaining. A+++++
http://en.wikipedia.org/wiki/Baroque_cycle
EDIT:
http://nealstephenson.com/quicksilver/reviews.htm - I know it's kinda corny to post this... but they're right