Very many thanks for all the contributions guys, everything suggested is most welcome, especially the cake stop!
I've finished my initial planning of the holiday now and one thing I immediately found out was that finding accommodation in N.I. exactly where and when you want it is very, very difficult. Places like Port Stewart are almost impossible. So my original plans of stops in Port Stewart, Omagh and Belfast have had to change to Larne, LonDerry, and Belfast (with great, great difficulty). Of course this is made much more difficult when looking for somewhere with bike parking for four, as most of the City Centre hotels have no parking facilities at all.
Anyway without giving the game away of exactly where we'll be and when (although I will if you PM me) we'll be at a lovely little hotel outside of Larne, a national chain in Londonderry, and a great looking B&B in the Belfast suburbs. All that comes after one night stay in Dumfries on the journey from Hull to Cairnryan, and another stay at the same place on the way back.
Initial plans of what to see etc are 1) The cake shop at Ballintoy! 2) The coast road in general, 3) Joey Dunlop's pub, 4) Giant's causeway. 5) The rope bridge 6) The Sperrins 7) Donegal generally and of course all the usual Titanic stuff etc etc in Belfast. We'll be there for 2 weeks which should give us nice relaxed easy peasey holiday.
Keep the contributions coming guys because even if you're not in the list above I've noted everything you've said (that sounds a bit like a BBC phone in show but I do mean it).
Cheers all.
Riggers.