Which seasons' casts should have had more people return?

I've heard a lot on theis sub about how seasons like Guatemala had good casts, but none of them ever returned for later seasons. What other casts do you think should have had more people return? Personally, I think more people should have returned from Marquesas, Vanuatu, and Gabon.

On the other hand, what seasons do you think had too many people return to play again? I think Australia had a lot of returnees that weren't that interesting and shouldn't really have returned, but that's just me. Thoughts?