Help with Possible travel itinerary through Ireland

As your itinerary seems set, IMO you seem to have plenty of fun things to fill your time. Plan for longer drives than Google Maps says (everytime it took us longer than Google Maps said as roads in the West are small, villages have traffic, lots of twists and turns.) And if you are going in Fall, the weather will add even more to driving times.

I'm assuming it's Howth you will be going to? I haven't heard of Howth Island. If it is Howth, it's a beautiful little village and a super easy day trip by train from Dublin Centre (driving there can take a while as it's just city roads.) There's the castle, the cliff walk and so many delicious little cafes. Wicklow gardens/Avondale are in a completely different area and can take a lot of time to get to from Howth or Dublin Centre. I do not know how you could fit both Howth and the Wicklow area in one day. Google maps says it's a bit more than an hour from Dublin but do not underestimate the traffic in and around Dublin. There is SO much traffic. Honestly, I'd pick either Wicklow or Howth. Both are lovely. One is rolling hills, the other is seaside.

Thank you for your input. I was trying to determine if the outline of trip was realistic or too much to do in that amount of time. And trying to decide whether to go to Howth or Wicklow area? It is so overwhelming when we have never been to Ireland reading all the travel guides and maps and determining what is worthwhile and how much time to allow for everything.

Nothing is set in stone other than our airline flights! And being in Dublin for St Patricks Day parade...

For me, this is way too much for your short amount of time. For you...? You will be in your car, driving, for a large portion of this itinerary. While I love driving in Ireland, this is too much time spent on the roads for me. And the traffic around Dublin is awful. Is there a specific reason you want to drive down to Kenmare? If not, you might stick to the East coast (Dublin through Wicklow to Waterford and back to Dublin.) Or head to Galway for 2-3 nights (much easier, fast freeway though bus/train are equally as quick) with a lot to see and is also on the Wild Atlantic Way. Then back to Dublin. You will spend less time in your car and more time exploring Ireland. And, I'd recommend not having a car in Dublin if possible. It will take you an hour to drive one mile (I know I'm harping on the traffic again. Lol!)

You have a very ambitious itinerary. In Kilkenny, The Butcher is very good for steaks. We also ate at Ristorante Rinuccini which was Italian and quite good. On Day 3, the Gap of Dunlow could take up most of the day and you won’t see much if it’s cloudy and rainy. It took us most of the morning to do Ross Castle, Muckross House and Gardens and the jaunty cart to the falls and we were staying in Killarney not coming from Kenmare. Day 4 may take more time than what you have down because the roads are narrow and twisting. I suggest you keep your itinerary but not be upset if you have to adjust as time allows. Have a great trip!

I personally think this itinerary is very ambitious. You'll be spending much of your time in a car and the sun will set around 6.30 pm. I doubt very much you will be able to drive from Kilkenny to Kenmare via the Rock of Cashel, Cahir Castle and either Cork or the Beara Peninsula in one day. That is alot of driving on some very narrow roads and through potentially very busy cities (Cork). You may want to stay in Killarney instead of Kenmare just to reduce a little of your driving time. To further save time, and actually have a better experience, skip the Cliffs of Moher and go to the Kerry Cliffs instead. If you are staying in Dublin how do you plan on getting to either Howth or Wicklow? You do not want a car in Dublin City Center. If you are staying in Dublin City Center, drop off the car and plan on taking a taxi or public transit to Howth. I'm not sure what you mean by Wicklow Gardens. Do you mean the botanical gardens? Powerscourt? For either you will need a car or to take a day tour.

I agree with Trotter - you're trying to cover way too much geography in much too short a time.
To keep from running yourselves ragged, and spending most of your time in the car, I'd suggest concentrating a single area. Basing yourselves in Kenmare is a good call - easy access from there to the southern half of the ROK, Killarney NP and the very pretty Beara Peninsula. Killarney town would work too.
Could maybe split time with a night or two near Dingle to enable a leisurely drive around Slea Head and the Gap of Dunloe.
Catching one of the daily RyanAir flights directly to the Kerry airport near Killarney upon arrival in Dublin would save you the long drive across the island and back, and the return flight back to Dublin would be a hassle free way to get back in time to enjoy the St. Pat's day festivities. There are numerous rental car outlets at the Kerry airport which would help to streamline your logistics somewhat.