Sulfur Caves suggestions.

Make hot springs generate above sulfur caves. Maybe not above every cave, but make it a semi-common appearance. The sulfur spring is quite boring on its own as a biome marker. Having an entire surface biome of large pools and the corresponding blocks would be visually stunning. Maybe incorporate tiered pool layers like the Ludh cave biomes do to spice up the variation.

Speaking of the sulfur spring. As it generates now, it should spawn inside sulfur cave caverns. I think it would make the biome more interesting. It would make the potent sulfur block more common as well.

I am glad to have another Volcanic related biome in game, but it's lacking in features, like many other biomes. Please make this biome so much more than what it is. Minecraft could use grand and awestriking things to see.