David - as I recall, I played N&P on your recommendation! As for Cruit Island, I think Dr Johnny Brown - occasionally of this parish - pointed me towards it.
Sean - I can't recall the exact timings, but apply the general Irish rule that everything is fairly slow! How long are you planning to travel for? I am not sure that you want to be trying to do Derry and Donegal in the same, shortish trip.
In two separate trips I have played both courses at Ballyliffin, Portsalon, both courses at Rosapenna, Cruit and N&P - all are good courses - and, of course, once you go East of Derry you get to Portrush etc.
Those courses are all before you get to Donegal, Rosses Point, Enniscrone, Carne etc - hence my thinking that you would ideally need two trips, one to do the courses closer to Derry, the other to do the ones which are a bit further west and south, but still essentially in the north-west.