Mandvi is a port town with a long beach, a palace in the dunes, and yards that still raise wooden ships. The old town is for lunch and a walk. Wind turbines along the coast are scenery on the drive, not a stop you need to collect.
From Bhuj it is a comfortable day there and back. The full cluster is Mandvi beach & royal Kutch. It sits naturally in a three-day first visit after the Rann and a Bhuj town day.
If you want a cleaner, less crowded shore, go to Ravalpir Beach instead of the main Mandvi stretch. There are no shops and no water activities. What you get is a quiet, clean beach.
72 Jinalaya Jain Temple is worth the stop if you are Jain. Others can leave it off.
Skip Shyamji Krishna Verma Memorial & Museum and Godhara Ambe Dham Temple. They are neglected and littered — not a family stop.