(I love Killarney too)

a bit of research on the Wild Atlantic Way may be worthwhile...a road trip north through County Clare up to Galway would be fantastic. (there's a place called Vaughan's Lodge in Liscannor that serves...sorry jt...the best fish & chips I had in all of Ireland)

Doolin is also a fantastic place not far from Lahinch and the Cliffs of Moher
that has some great restaurants and pubs for music.

That's a LONG haul from Cork/Killarney to Belfast...and I'm not sure it's worth it

And enjoyed every part of it. I'm coming around to the notion that Belfast is just too far in the time available.

I'm kind of being sarcastic and kind of being serious.

What's really cool is that you can't go wrong with anything you do over there. I'm heading over for golf this next June...but someday, I'll be heading up to the NW part of Ireland and exploring those areas and playing some golf as well.

We have family in Letterkenny, Rathmullen, Buncrana and various other places in Donegal.

I think we already discussed golf up there.

Ballyliffin, Rosapenna, and Portsalon are good links courses. We play a few local courses as well (with family that are members). They aren't really worth going out of your way.

Hard to go broke golfing up there unless your heart is set on Portrush.

I'm not sure I've ever driven more than 2-3 hours on an Irish Motorway

In theory it's possible - I would do it bright and early so you can lunch at your destination.