We loved Rock of Cashel, Blarney Castle (and kissing the Blarney Stone!), and getting a bit of time in Cork. However, don't book on a Sunday because the English Market is closed. Without it, there wasn't much to do other than shop and get a quick bite to eat.
If you want to kiss the Blarney Stone, you can actually do it for free, have someone film you doing it, then go to the bottom to see if you want to purchase one of their pictures of you kissing the stone for €10. That way, if you don't like their pics, you still have the video on your phone. Don't pay any money unless you want their photo that you see before purchasing, and if so, pay at the bottom. I will say, the staircase to the stone is very windy and small. People with mobility issues may struggle.