In reply to dctarrant2000:
Another vote for Cala Magraner, one of our favourite crags when our kids were little, with climbing straight from the beach. Just a couple of caveats - the walk-in is easy but fairly long for a small child, especially uphill on the way back. Also, depending on sea conditions there can occasionally be a lot of seaweed, which can make the beach experience a bit disappointing.
You could also try Hairpin Wall (Caimari). Not usually a destination crag, but very accessible!