What would you recommend for a pair of decent flat pedals that would be on a bike that's used mostly for casual riding down to the coffee shop but sometimes for some good exercise? I have clipless pedals for my newer road bikes, steel clips for my vintage road bikes but then have an older mtn. bike and a steel bike that I've left the original pedals on. They are decent enough when I'm just doing a casual ride with my wife or in town for a coffee but not great for more extensive riding.

I need to keep the pedals flat because my son will ride them sometimes and I don't want to be wearing cycling shoes when out for a coffee with my wife.