We have 3 nights in Killarney.
On the first day, we will driving from Dublin to Killarney and will stop at Rock of Cashel and Blarney Castle along the way.
On the second day, we will dedicate to Killarney National Park and hopefully, stop at Kissane Sheep Dog Farm.
What should we do on the third day? We are planning to stay the night in Killarney but it is not set in stone so I appreciate all your ideas.

My original thought was to do a Dingle day trip and stay in Killarney again BUT after reading several forum posts, it is not recommended. Too long, too much driving.

After Killarney, we want to see Cliffs of Moher and Burren on the way to Ennis, our last day in Ireland.

Muckross House and Muckross Abbey are not far from Killarney.

I still think your last day is way too much driving so relax and don't go too far before your epic journey to Moher, the Burren and Ennis.

Thanks mjdh1957. For our last day, how would you break that up to lessen the driving?
We are flying out of Shannon the next morning (early flight).

I'd aim for either the Burren or the Cliffs and not attempt both on the same day.