When driving on the Ring of Kerry it is tempting to just stay on the N70. The Ring is 160 km, so doing it all in a day will make you want to set some preferences. Well-known detours are Valencia Island and the Kerry Cliffs near Portmagee. However, hopping off at Cahersiveen will get you to an area with some nice old landmarks without taking too much of your time. In just a few minutes driving from the town centre, you will find 3 places worth a visit: 6th-century Ballycarbery Castle, Cahergall Stone Fort (600 AD) and Leacanabuaile Stone Fort (850 AD).
You may also want to relax a little on Whitestrand Beach or take a few hours extra to climb Knocknadobar (690 m) and enjoy the most magnificent views.