Personally, I like the GeoStrata stones (granted, I use a texture pack so I don't even know what they look like without it). I don't use the Chisel mod, but I would like to see them craftable into stairs or slabs.
Regarding the stone generation, I don't think you can disable it. There's a statement from Reika in this thread regarding the decision to remove that part of the config.
Stairs and slabs won't come untill 1.7, sadly.