I would rank them:
1. Walls
2. Furniture
3. Resources
4. Misc
5. Weapons/Armor/Tools
I don't think everything needs to be super differentiated. Just being able to see the difference between broad types like metal, leather, stone, and wood would be plenty, imo.
For armor, being able to see the difference between a bronze piece and a leather piece would be kind of nice. Just having different colors is plenty for identifying them most of the time, and I don't think they're really used for decoration. I kind of think that weapons and armor are the least-commonly seen tiles out of the options.
I'm not really sure what the current resources look like, but it might be cool to have different tiles based on if something is a gem, metal, coal, or flux, or whatever. Maybe there could be different-sized gen tiles based on the value of the gem.
I think furnature could be a good one to have more options for since it is used decoratively and they are used all over the fortress. That bone furniture looks nice.
I really like your idea for having a special tile for wood walls. I'm guessing you'll keep natural smooth walls so that walls of different stones will blend with each other, so this will mostly be for constructed walls. I'm not really understanding why a gold walls would need to be different from an iron wall, and i kind of doubt that metals would be used for walls enough to make two different metal sets of walls worth it, but i'm still interested in it.