The Gersten In Dreams is only 116 pieces, but it's a satisfying hour for an adult puzzler. It's challenging puzzle cut has no explicit connectors, just hexagonal-snake pieces (see photo below) that intertwine. Took us 12 rounds to make it so the puzzle would be tightly connected when finished.
The Art of Painting by Vermeer is a more meaty 325 pieces. It's got themed whimsy pieces and a little postmodern crackerjack surprise - you'll have to get it to see what I mean (and if you managed to skip all those liberal arts classes in college like me to hang out in labs, here's a great Intro to PostModernism to add to your xmas gift list).
However, I'm not super-happy with the colors of the Vermeer, but we just couldn't do any better on this one - we brightened it a little to get the details to come out (these old paintings are so dark!), but we just couldn't get rid of a slight purplish hue that came as a side-effect.
Lastly, if you want the The Tall Towers or Bokuyo Forest for Xmas, we're trying hard to get them in stock but it's not looking good. At best they'll come into stock like December 20th. At worst, they'll be in stock right after Xmas.