I can recommend the following itinerary in Ireland after a couple of memorable trips last year.
Day 1 - Newtownards lunch - Donegal evening. Fly via north coast for great views of Donegal and Scottish islands (vis permitting)
Day 2 - Early start - Abbeyshrule or Ballyboy - Weston for lunch - Newcastle
Newtownards - no problem getting taxis for a 5-10min journey into town for lunch
Donegal - we stayed at the An Chuirt and had a good meal and plenty of Guinness
Abbeyshrule - friendly and beautiful
Ballyboy - very pretty
Weston - The restaurant might now be open, otherwise Dublin is your oyster
VFR routing out of Weston is via the Liffey River through the centre of Dublin - fantastic!
Remember your GAR forms for both the UK and Ireland. Donegal kindly allowed us to fill them in on arrival after I emailed details in advance.