Biggest thing you are missing: wireframes! You gotta show that stuff to show that you are keeping your models optimized. Texture sheets are also nice to show so that people know that you use your space wisely.
The Mayan scene is real nice, the thing that bothers me is in the 2nd shot the huge black shadow staring in your face on the tree. If the tree is on the foregrownd, show off its textures instead of showing a lighting mistake. Dont get me wrong I really like the lighting in the scene overall, just that particular shot. Also there is something awkward about the wires on top in those concrete blocks. Its coming out and going back in like a snake, and i dont think its supposed to do that, i think they would just stick out, even if its bent. Hope that helps. Overall its not bad, I would have liked to see more textures though. Hope that helps. =)