Ha ha ha, this subject is a standing joke in my family. My mum says my dad should write a book about all the public toilets in England cos he's sure to have visited them all! Jokes aside, how often are you dying for the loo when you're shopping in town and there seem to be no list in circulation so I'm gonna start one!! I've called this "Toilets in Dublin-issue 1" so that I can add to it as I find them!
So for starters, off the top of my head here's the first few, and most of them are in department stores.
1. Boyers 22 North Earl Street, D1 - on the mezzanine floor through the linen section to the rear.
2. Clerys 18 Upper O'Connell Street, D1 - 1st floor to right by tea room
3. Arnotts 12 Henry Street, D1 - 1st floor to right of escalator next to cafe
4. Marks and Spencer 24 Henry Street, D1 - on the top floor (?)
5.Connolly station- large number to right of ticket barriers or in bar to left
Over the river
5. Brown Thomas Grafton Street - lovely bathroom, next to cafe on 2nd floor(?)
6. Marks and Spencer Grafton Street -through homewares
7. Stephen's Green Shopping Centre
8.Pearse Street Station- on southbound platform

Toilet in Bar Pintxo in Temple Bar- guess you can't just wander in only to use it but it surely deserves the title of the "throne"!
I'll tackle hotels, bars, galleries etc later as some of them need a certain amount of "I'm walking in here and I know where I'm going" attitude to avoid the "toilets only for customers" comment.