So I am looking for some advice for 1 night of our upcoming Ireland trip.

Our plan is to drive the Ring of Kerry on a Friday and spend Friday night in Kenmare.

For Saturday, we currently plan to make a morning drive to Kenmare, spend the night there, and then head to Cork Airport for a 7:30AM flight Sunday. However, on 2nd thought, that would mean we'd need to leave Kenmare around 5am to drive to the airport, return the rental car, and check-in for our flight.

Would it make more sense to just skip Kenmare and drive into Cork for the day and night, and be closer to the airport? We also want to get to Blarney Castle, so is it practical to leave Kenmare early, go to Kinsale for a few hours, go to Blarney Castle, and end up in Cork city or near the airport for the night.

Thanks.

There is an excellent Radisson Blu hotel just across the road from the airport terminal at Cork Airport. You could return your hire car the night before and walk to the airport from the hotel the following morning.
If the flight leaves at 7.30 am you need to be at the airport at least two hours before hand, check what your airline recommends for that.

It's quicker to get to Cork airport from Kinsale than from much of Cork.

I doubt you really do need to be at the airport 2 hrs early - but, allowing for driving time on Irish roads, time to check a car in and then for getting across to the terminal, leaving Kenmare at 0500 is very foolish. Even I would want to have left by 0400 - which is dunderheaded, and therefore means overnighting somewhere a great deal closer.

Check what time you really do need to check in for the flight, and what times the car hire place opens, then overnight either at the airport or in Kinsale. Personally, I'd far rather stay at Kinsale if the logistics allowed it.

Thanks... I had a bit of a brain lapse... I meant Kinsale, not Kenmare!!

Meaning... we are driving the ROK on Friday and staying Friday night in Kenmare.

Then, we had thought about driving Saturday morning to KINSALE! So question now is whether we could leave Kenmare in the morning, go visit Kinsale, then go to Blarney Castle, and then end up in Cork.
Or, perhaps differently, leave Kenmare, then drive straight to Blarney Castle in the morning, and then down to Kinsale for the night...

sorry about the confusion!

Still, you need to check
- hours of rental car return (if after-hours drop-off is an option)
- precise wording of airline re. check-in times. Cork is a small and well-organized airport with an easy layout. As flanner said, 2 hours is a huge amount of time at Cork. Airlines often state that their check-in counters do not open until 2 hrs prior to departure. Which does not mean that you have to be in line precisely T minus 2 hours.

So, IF you were able to drop-off your car late Sat night, I'd start with Blarney Castle (or kiss any stone you see en-route and save a lot of money and time), then visit Cork during the day when everything is open, and spend the evening in Kinsale. And go to the airport after dinner in Kinsale, drop off car, stay at one of the airport hotels.