Ireland Itineary HELP

What a whirlwind trip! But if you love castles and grounds, you may not be giving yourself enough time for Blarney or Rock of Cashel. The grounds at Blarney are immense, and are a shame to miss. Rock of Cashel is stunning—we spend an entire afternoon there.
If you drive the Ring of Kerry, I’ve heard that if you drive it “backwards”, the traffic is much better. All the tour buses tend to go just one direction, so you wouldn’t be caught behind them. However, I wonder if you would miss some of the views because of the buses going the other way blocking you.
Whatever you do, though, you will probably have a great trip! I’ve been twice, and I’m going back next year—and I’m not even Irish! 💗☘️🇮🇪

Just a couple of quick thoughts. You may want to rethink renting a car upon arrival in Dublin and then driving into Dublin. It’s difficult to drive in the City Center and very difficult to park. My suggestion would be to bus or taxi into town and then rent a car from town on your way out. Second, instead of staying north of Dublin on your way back, why not stay south since you want to go to Wicklow and Glendalough. You’ll be driving by there on your way to Dublin anyways. Finally, check how much daylight you will have in September. The 12 hour day out of Killarney may mean some night driving.

Why Air bnb? Why not stay in one of the places in Rick's book?

An additional thought. You may want to consider alternatives to Airbnb. Ireland is in the process of adopting restrictions on short-term rentals. Here's a thread from a few days ago on that topic. https://community.ricksteves.com/travel-forum/ireland/airbnb-in-ireland-4d2d2896-2497-4a8d-84d7-4e9c3887b79f

Tabitha, most of your itinerary seems good until you get to the 11th. I think you might have a bit much on and your not going to make it all happen as you want. You will probably need at least 2.5hrs to have a good experience at each of the places you might find interesting. If you had another two days I'd say go for it. The distances in Ireland are not that great but if you get stuck behind a couple of tractors on skinny roads or if you see something that you just have to look at suddenly your 87km journey which should take an hour has turned into a 4hr + trip (like getting out of the car to spend a minute taking a photo and having the car's security system lock you out with the keys still in the ignition). If you do the day as you have planned, at the end you are going to be completely worn out as the trip will be very rushed and you may end up having a trip that you can't remember very well.

So I changed the end of our trip ….

Sept 11 - Leave Killarney to Dublin castle (be there when they open I believe at 9), spend about 3 hours, drive 1.5 hours to cashel, explore Rock of Cashel for about 3 hours and drive to Killkenny (45mins) and spend the night.

Sept 12 - Drive from Killkenny to Glendalough upper Lake and explore then drive to Dublin, return the car that night and stay in the hotel near the airport.

Sept 13 - Go to airport and fly out at 11am.

With this I took out the titanic experience which I'm a little sad about because it is a fascination of mine but I'm just not sure if it is worth it.
Do you think it would be too much to still go to the titanic museum that day? Maybe just do the titanic museum first and not be at the Blarney castle when they open?

We were very much disappointed with the Titanic museum in Cobh. Really not worth your time in my opinion.

With the revisions, it is busy but doable. Just give yourself permission to linger, add, and skip, as you feel like. Cobh is nice but you can’t do everything - and you have some beautiful places selected.

Second picking up your rental car as you leave Dublin. We stayed at Waterloo house near the Grand Canal (Baggot Street) and booked our car through AutoEurope - a Hertz vehicle and the agency was just down the street from our hotel. Egress from Dublin fairly easy but our Monday departure was a bank holiday, less traffic than normal.

Most of our movements in Dublin were via Uber (essentially they send a standard cab to you at the normal cab rate) if too far to walk (or too tired to walk).

Seems the cab ride from Dublin Airport to our hotel was about 20 Euro. The Aircoach would have taken us very near our hotel for not a great deal less - went for the convenience after the longish flight from Atlanta.