Feedback on a short, tentative itinerary for a parent and kid trip?

Some thoughts:

Since you are heading southwest out of Dublin, you can rent a car that direction and save heading out to the Airport, backtracking, and paying an extra 30 euro for an airport pick up.

I think Ring of Kerry isn't needed if you visit Dingle peninsula. My first trip we did Ring of Kerry on a bus with no stops for points of interest. I came away thinking I'd have traded it for Dingle/Slea Head.

The places you might enjoy adding are Clonmacnoise or Glendalough to see a uniquely Irish monastic settlement. Other Abbey orders came from Europe later.

I think Rock of Cashel is an important sight and not out of your way. I expect to stop at Kilkenny, also on that route. I'd also suggest considering a day trip to Newgrange while in Dublin. I took a tour from the Busarus station with Bus Eireann and consider it the highlight of my first visit. They also have day trips to Glendalough.

On your way back to Shannon (edit), if you have time, you could visit Bunratty castle. It's a good tour and has many old houses (moved here from around the country). They also have a dinner show in the great hall. I didn't go but people said it's fun - if cheesy.

I'm personally wouldn't do Killarney for one night and then drive an hour away to Dingle for two nights. If you plan on doing both the Dingle Peninsula and the Ring of Kerry, it makes more sense to base yourself in either Killarney or somewhere right between the two for three nights (frequent poster Robert usually suggests Castlemaine, which is a good choice). Still, even if you stay in the Killarney area you're not far from either the DP or the ROK.

My take on the Ring of Kerry is this...if you're only going to follow the typical route that most coach tours take, it's not too exciting. The best things to see on the ROK are not the touristy areas. From experience I can suggest the Geokaun Mountain & Fogher Cliffs, Ballycarbery Castle, Kerry Cliffs, Ballaghisheen Pass & Ballaghbeama Gap, Moll’s Gap, Black Valley, and the Gap of Dunloe (big with tourists, but coaches can't go through). All of these can be seen in a day.

We took our 8 and 11 year olds to Ireland in the summer 2016 and my son and I ( then 10) went back for a week in Dublin last summer.

Here were the highlights:

1) Dublin: Dublinia, St Stephen's Green, Butler's hot chocolate and truffles, Murphy's ice cream, Kilmainham gaol, the hop on and off bus

2) outside of Kilkenny we did the Dunmore cave. It had not been on my radar but a Dublin cab driver told us stop and it was great! We unfortunately did not have time for cashel ... next time :)

3) We really enjoyed Killarney National Park. We rented bikes and biked to Muckross house and farms, Torc water fall. We also did Kissane Sheep farm but I see that they are not open when you are there

4) We all loved the Ring of Kerry so I say do it. We stopped and had a picnic lunch on the beach. My daughter swam, the rest of us played in the sand

5) we also enjoyed the Dingle peninsula

If there is any way that you can squeeze in the hawk walk at Ashford Castle, I would try and do that. We talk about it all the time. One of the coollest things that we have ever done!

Have fun!

Many thanks to all of you for taking the time to reply. I've incorporated your suggestions (or versions of them) into our itinerary, though a few ideas will have to wait for next time. I'm really looking forward to it!