I agree regarding the cement block spam. I'm sure most of those custom tilesets have their own solid blocks you can use. I know that cloud tileset seen in the screenshot with the Sumo Bro does. In that screenshot with the solid blocks under spikes, it would look better for there to be solid ground under the spikes. I really designed those to be placed on the ground/ceiling like stalagmites/stalactites. You should also consider using the corner tiles to connect the different chunks of ground/ceiling.
This is the screen I'm talking about where the spikes would look better with ground under them.
"Experience, lad. You should learn to appreciate it."
-Kup, Transformers: The Movie 1986