I think a two (or more) semester course where you write some libraries/functionality during the first semester from a blank page, and then use/refactor/enhance

I think a two (or more) semester course where you write some libraries/functionality during the first semester from a blank page, and then use/refactor/enhance that code in the second semester would be very valuable. "Eat your own dog food" is something everyone should learn in school. Perhaps the third semester could be based on getting some other students code to enhance as well as being a resource for someone using your code from the previous classes.