@susan.james I also am apprehensive about giving students too many exemplars out of fear or "stealing" their ideas. That being said, when I have done this activity with students, they did not struggle with picking a different topic. I emphasized it should be something THEY care about or like - I have had students do things around basketball, or ballet, my favorite was one student who did it on a "Target Run" (here in Minneapolis, we LOVE our Target!).
I would say one thing some students struggled with was picking a diverse set of ways to encode something as well as the reasoning behind it. For example, I had a few students who said "ASCII" for absolutely everything - I was looking for more diversity. Other students just said it would take 10 characters to encode a name with no real reasoning behind it. I think next year I might consider asking students to peer review one anothers's work or make a requirement around justification or number of different methods used to encode the experience.