I started on this one last night and it's going amazingly quickly. I just finished the sky and the edges of the rock formations that border the sky.
Educa Monument Valley - 1000 pieces
Total time: 5 hours, 9 minutes
At first I had an issue with some edge pieces that didn't fit in, but I eventually found the right spot. There seems to be a pattern to the cut such that pieces fit where they don't actually go.