First, I do not intend to derail your thread and I hope you get some good ideas.
Generally, I never understood rush "themes" even when I was a pledgemaster for APO. I just feel like if your coed is for majors, or for service, or whatever, just having a general theme like "Brothers and Sisters in Business" should be good enough.
HOWEVER,
My one contribution is "007." My chapter seems to have done a James Bond theme once. I feel like tuxedos and martini glasses were incorporated into the branding somehow.
In later years, they started getting more quirky. They were the originators of the following meme:
For better or for worse, that's my chapter. lol