Are there any assignment repositories that you use for assignment ideas? I am aware of the Nifty Assignments from Stanford and have used several. There are a lot of good fine grained problems on HackerRank, but I would not incorporate the work of a commercial group into an assignment.
Ideally, they would come with a write up and be licensed for general reuse with inclusion of a standard disclaimer, etc. Assignments with multiple parts so students get to live with their own code over a period of time would be great.