18ga to 14: Used primarily for ball dancing or similar activity. These are too small for suspension unless a very large number of hooks are used.
12ga to 10ga: Sometimes used for horizontal suspension, but usually too small for vertical suspensions.
9ga: Common size for horizontal suspension, sometimes used for vertical suspensions as well.
8ga: This is the most common size for most suspensions and can be used for almost anything.
6ga and larger: Normally used for two- or one-point suspensions, or in vertical suspensions for larger individuals.