Cahir castle OR Rock of Cashel or both?
 

We are planning a two week trip to Ireland, and working on an itinerary. Rock of Cashel and and Cahir Castle both seem interesting. Would it be too much to visit both on one day ( e.g too similar?) if we decide to do both of them in one day, is there an order of preference (better to do one before the other? How much time would you recommend at each place?
Appreciate any information
Thanks!

We actual did both in one morning. Got to the Rock right when it opened and then went over to Cahir Castle later in the morning and then had lunch in a cafe across the road from the castle.

They are not too similar.

Unless you have a specialist's interest in the history associated with the buildings, each vist might interest you for 1-2 hours - so half a day is plenty for the average visitor. There isn't an obvious sequence for the two visits - go with whatever fits your route better.