Just saw this thread so I thought I would weigh in as EP and I had similar Scotland trips in 2023.
Took my first overseas trip to Ireland in 2022 and was fortunate to play:
Ballybunion
Waterville
Lahinch
Port Stewart
County Sligo
Royal Portrush
Royal County Down
Including travel this was a 10 day trip with the biggest time sink being the travel from south to north.
I would definitely play all the course again and have another trip to Scotland planned in 2026 before I can think about Ireland again.
Other courses I would consider
Old Head - I hear it is great piece of land, but only a mediocre golf course. Very south and not easy to get to. Not a first trip course, but worthy on a 2nd trip
Hoggs Head - near Waterville and one we should have added to the first trip. Very exclusive
Carne/Ennescrone - between southern and northern Ireland. A good mid country stop like County Sligo.
Portmarnock - In Dublin, would be easy to include on the way in or out.
All of these will be on our next Ireland trip along with RP and RCD. While I have played RCD before, it was raining sideways so I need another crack at it.