If you want to be somewhat off the beaten path go to Carmel River State Beach. It's at the southern end of Carmel where the Carmel River empties into the ocean. This beach is actually part of a nature preserve so be prepared for lots of birds/waterfowl, fish, crabs, etc. - all of which are special. The sand at this beach is not the white, sugary sand of Carmel Beach - it's more natural-feeling. The beach is very low-key and when we were there it had lots of kids. There is a lagoon-like area that is created by the beach itself (again, filled with birds, etc.) and the kids were in kayaks, on paddle boards, etc. so this area is perfect for the youngsters - and there were several young folks just enjoying the water.
Pack a picnic lunch because this is on the edge of Carmel and a ways away from the main shopping/dining area, but it is beautiful. We had a very pleasant time.