Ring of Kerry and/or Slea Head? Looking for suggestions!

You don’t mention where you are flying in from or the rest of your itinerary, but I fear you are doing what most americans do when they travel overseas! Rush, rush!
IMHO, skip the ROK this time and head to Dingle. You can then do Slea Head drive. The ROK can be done in one day, but shouldn’t be. And if you did do the ROK then you were going to drive to Dingle?
I hope you have allowed more days than just this one to relax!

Oh yes, definitely other days without driving, albeit not many! Our itinerary is as follows:

Fly into Dublin April 19th - stay here for the day/night
April 20th - pick up rental car, drive to Kenmare stopping at Blarney Castle along the way.
April 21st - ROK or Dingle (as mentioned in original post). We would drive to Dingle once we hit Kilorglin - not exactly sure what time of day we would hit this point.
April 22nd - Dingle
April 23rd - head to Doolin at some point in the day
April 24th - Cliffs of Moher
April 25th - drive back to Dublin at some point in the day
April 26th - Dublin
April 27th - fly home

Oh dear, this is quite a bit of driving.
If you are flying into and out of Dublin, could you be persuaded to see the east coast side of the island? Perhaps spending time in the Wicklow mountains? If you go south you could go to Kinsale, Blarney castle, but I would not try to drive all the way over to Dingle and Doolin!! Far too much driving! Avoid one night stays! They are time killers!
Perhaps heading norh to New-grange/Howth?

It is a bit of driving, but up for it! Thankfully I’m from an area where long drives aren’t uncommon. I’d also hate to cancel all of our reservations and rework our trip just a few weeks out, but maybe that’s my stubborn side 🙃!
We don’t have too many one night stays, I cut some stuff out of my original itinerary to make sure of that. Maybe we are being a bit ambitious but I suppose we’ll live and learn!

I think you have enough time to enjoy both the ROK and Slea Head and Dingle town. We have been to Ireland several times. On one trip we drove ROK one day, stopping several times for views. The north side of ROK isn't as scenic as the south side, so that part of the drive won't take as long. Leave late afternoon and head for Dingle town for dinner and overnight. Next day, get picnic supplies in Dingle town, then drive out to Slea Head,stop at the Blasket Island visitors' centre, then continue along part of the north side of the Dingle peninsula, and head back to town for another dinner.

Yes, the roads in Ireland are very slow, but also keep in mind that the entire island is the size of Indiana.

You don't need an entire day to visit the Cliffs of Moher.

If you must choose between ROK and Slea Head, we found that ROK was more scenic and the landscape was more varied.

I second what Cynthia has said. You will hear it said that you can’t see all of the ROK in a day and that is probably true. However, you can see many of the highlights in a day. Yes, it will be a lot of driving, but not everyone has the luxury of spending a couple or 3 days in this area. The next day will give you plenty of time for the Slea Head drive and visiting the town.

Will you be in Doolin for two nights? The Burren loop is very interesting, but one of our favorites is the drive out to Loop Head, great if you like huge waves crashing onto rocks. (We do!)

We will just miss you in Kenmare. Where are you staying?

I’m definitely OK with not seeing the whole Ring of Kerry, as long as I could hit some highlights I think I’ll be happy 🙂
We could definitely do Slea Head during our full day in Dingle, however I was hoping for a day off from driving (especially since my boyfriend isn’t too keen on all the driving). This is why I’m wondering/trying to decide if I should choose one over the other. Of course I’m having the age old dilemma of missing something spectacular in either place! I suppose this is something we can decide on when the time comes. The luxuries of having a car!
We will have 2 nights in Doolin as well. Any suggestions for what to do after the Cliffs? As Cynthia mentioned, we won’t need a full day for that. Not sure we’ll want to get back in the car though.
We’ll be staying at Watersedge Guesthouse in Kenmare. I had family stay there last year May so it came recommended 🙂

You can't see everything .....and trying usually is very self defeating. Yes you can drive the ROK In one day. First the driver won't see a ton because they will be concentrating on staying alive. The roads are very doable but are challenging and need full attention at all times. So you will be whizzing past amazing sights not being able to really explore and soak in real wild Ireland. Can it be done - sure. Can you get enjoyment out of it - sure. But for me it would be tiring and insanely frustrating.

I'd urge two days in Dingle. You will still see insane scenery, have access to wonderful small town Ireland and great historical sights. If there DO NOT skip Slea Head and viewing the Blaskets. It would be like staying minutes away from the Grand Canyon but skipping it. Yes you would miss the ROK....but you're also missing the Wicklow Mountains, Glendalough, the Cliffs of Kilkee, the wonders of Donegal etc etc.,
Thoroughly enjoy what you can see and don't regret what you can't. There is ALWAYS more....and the quest for it usually greatly diminishes the enjoyment of what could be magical.

At Doolin if you have an extra day consider a day trip out to the Aran Islands. They are so beautiful and the 2,500 year old fort Dun Anghosa has cliff views far better than the pretty but tourist overrun Cliffs of Moher. It's a great day. Seeing the Clffs of Moher is nice but try and go early like 9am or late in the day after the huge herds of tour buses disgorge the throngs. Plus bird activity is better then too. Also the Burren is wonderful - either self explored or with some of the great local guides. Doolin also has great pubs, restaurants and trad music. We loved McGanns Pub for food, atmosphere and trad music. Their Irish stew was fantastic.

Hope you have a great time ! It's a spectacular area......Just don't spend too much of it in a car.

To get to the Aran Islands requires taking a boat, right? How long of a trip is it? My boyfriend gets motion sickness from sitting in the backseat of a car so I don’t know how he’d handle those waters (which I’m now remembering is why I opted not to make the trip out to Blasket Islands - as much as I would love to). It does look beautiful though and definitely something to consider!
As of now I think I’m leaning toward doing Slea Head over ROK, but I suppose we’ll see when the time comes. Would it be too much to drive from Kenmare and do Slea Head in the same day? We’d have a full day so I think it would be ok.

You could drive Kenmare to Slea Head in a day. But would you be going all the way back to Kenmare that day ? If so that would be a LOT of intense driving for one day. If you drive from Kenmare out to Slea Head then stay in Dingle or near Ventry it is much more doable.

If you take Bill O'Brien's Ferry service and go on their big fast boat there is little wave action and its fast....about an hour to the Arans. Only on severe days would it be a problem. Still it depends on what he can take. Our friends feared it and had no problem.

Just leave time in your day to stop and explore, don't ever allow a desire to see one more thing or a so called must see to force you into the car for unneeded hours and miss out on the real magic of a trip to Ireland.....which is found in the little lingering exploratory moments.....

No we won’t be heading back to Kenmare (just staying for the night). We’ll be heading to Dingle from there for 2 nights.

We saw Slea Head and part of the ROK - Lady's View? both lovely