Here are just a few ideas to kick around:
favorite Joe or Cobra tank
favorite vehicle driver
favorite aircraft pilot
favorite sub group such as tiger force, python patrol, ninja force etc...
favorite year of figs
favorite year of vehicles
favorite specialty Joe such as Psych Out, Doc, Main Frame etc...
favorite named Cobra such as Crystal Ball, Croc Master, Fire Fly etc...
Favorite Joe or Cobra play set
favorite fig that came with an animal
Hopefully Son you guys can use these ideas. Just doing my part to help out.