I would like a little more control with not only my fan but also my print speed on pieces that vary in thickness where a fan speed curve and print speed curve by thickness would help.
On some complex shapes I notice the print head can some times reverse its travel when printing and can leave a blob in a corner that's hard to clean up. Fixing this issue would be easy by adding a clockwise or counter clockwise print direction.
These two features would be significant for quality of complex shapes and models with harder to print materials.