The Moria set is pretty good, I've been saving Helm's Deep to make once I have reports and such done as a reward before the hobbit sets are released.

I eventually caved and got the Weathertop set a month ago. It's a fun build, with a clever and very interesting design to make it appear spherical, but unless you can get it for $50-$60 I cannot really recommend it. It is too small for the higher prices unless you are a completionist.