I personally never got around to a minor, but if I did I would have looked into Business or General Management. It depends on your interests, but a minor in Education couldn't hurt either.
I have an SM friend who is got a minor in Gender, Sexuality, and Women's studies because she was very interested in working on plays in that realm. If you have a genre of theater you prefer, consider getting a minor in that subject so you are more knowledgeable in that subject.
If you're considering working abroad, or on cruise ships, minoring in another language is great too!