I would like more flexible discount codes. For example I'd like to be able to have the same code which can give a monetary discount off my subscription boxes and a percentage off my one time purchases.

This is because I may give an offer say on Father's Day for the first month box half price or 20% off one time item purchases. The value wouldn't be the same in monetary purposes and I don't want to confuse customers by listing different codes for different parts of my shop.