QoL changes for the Sulfur Caves

The new cave biome is really cool, but there's always room for improvement:
If I was in charge of improving the sulfur caves without adding new stuff, I would first make them rarer but cover larger areas. I would also make them flatter to give more space for the pools to appear.
Then, I would make them appear only in warmer biomes, with an higher chance in mesas.
I would also add an ambiance fog and make the cave spider's spawn rate higher.