First problem: You are in a debate with your Wife!!!
Marubozo is spot on with the analysis. Follow his guidance and you will figure out what is most profitable and hence which way to go.
We had a similar issue with offering "full plates" or selling menu items ala carte. We found that our margin was lower on the "plate" price and many people didn't want all of what we were offering on the "plate". So we now sell individual menu items only. YMMV