Successful intern projects: 1. High value if completed. 2. Low risk if not completed. 3. Able to finish in allotted time (2-3 months). 4. Exciting to work on and talk about. Anything else I'm missing?
I think reasonable people can disagree w/r/t the portfolio piece part but given that the nature of an internship is offering career acceleration for labor optionality if you decide not to exercise your option I'd hope that you'd maximize on getting your intern a great next gig.