Try Duxbury beach it has everything you need.
Tks - but we are heading north of the city.
I love Wingaersheek. It is very family friendy. At low tide the water goes waaayyy out and there are tide pools with sand dollars, little crabs, etc. The snack bar is good, with some healthy options as well as hot dogs, chicken fingers etc. and there are bathrooms.
Parking can be a problem on summer weekends. There is a lot by the beach and an overflow lot nearby. On weekends when it fills up, they can close the beach to non-residents so best to have a Plan B.
It's a lovely beach. Very soft light sand and calm waters. Wingaersheek is very calm and you can walk out quite a distance. There are also large rocks to climb on/explore. My kids (7 & 11) do prefer the waves at Good Harbor, but we went to Wingaersheek a lot when they were younger.