S.R.
Carlsbad is a nicer town in general than Oceanside. Sorry, Oceanside.
I was just at the beach in Carlsbad on Sunday. We were in the area for a wedding. My in laws stayed at the Beach Terrace Inn, which seemed really nice and family friendly, right on the beach in Carlsbad.
I also like beaches south of there- Encinitas, and Del Mar is probably my fave. MissionBeach/MissionBay area has tons of rentals. And North of there in Orange County- San Clemente, Huntington, and Newport. We vacationed many summers in Newport Beach growing up. Its a nice beach vacay town. We were always crammed in some kind of rental beachhouse we would share with our cousins family. Sounds fun, I have fond memories of our extended family beach vacations!