The easiest solution is offering unisex bathrooms. Every bathroom in a private house is unisex, why bother making distinctions in bathrooms in the public sphere? Lawrence, Kansas has many businesses with two or more unisex bathrooms, and no one has complained yet. You could have separate bathrooms for families (like they have at big airports) that have more changing tables, etc. but other than that I think that just offering bathrooms would work for everyone.