Agree with everyone here. Find a pair of costumes that make both of you happy. Let her dress as she wants. Why should you have all the fun.
Magenta and Columbia would be fun. Actually, I want my wife and I to be them this Halloween.
My wife and I married on Halloween. For our 20th anniversary, we hosted a costume party. I dressed as a bbride. Un unbeknownst to me, my wife planned to dress as Columbia with a tux coat and a top hat fascinator. When I walked downstairs, she was the first person I saw. My immediate thought was "wow, she looks so hot!"
Please share pictures.