If you just want to "get there" via the most direct route then going via Adare is probably your best bet. It's a picturesque little place famous for its thatched cottages, but it's also a popular stop with day trippers and bus tours so it tends to get rather crowded around midday.
A possible alternative is the very pretty coastal drive down the N67. On a sunny day it's especially inviting with lots of pretty seascapes along the way - and with no crowds. The route will take you to the village of Kilkee where there's a nice stretch of sandy beach and a cliff walk that goes for a mile or so along a spectacular headland - lots of wide open spaces for the kids to wear themselves out.
There are plenty of places to eat along the beachfront or a little further along the road at Kilrush.
The nearby Killimer-Tarbert ferry crosses the Shannon - another diversion the kids might enjoy - and deposits you on the other side from which it's a pretty easy drive thru Tralee and on to Dingle.
The route takes a bit longer but is much prettier way to go if the weather cooperates.