Which has more resale value: a walk-in shower or tub/shower combo?

I’d like to put in a walk-in shower, but my wife says that we have to have at least one bathtub in the house or we’ll hurt our house’s resale value.

I would agree with your wife on this. If you don’t already have a bathtub elsewhere in your house, then in my opinion it will not only hurt your resale value, but also limit the offers you do receive. It would also potentially take longer to sell the home as you would narrow down your prospective buyer base. Hope this helps!