If you stay in Dublin and travel to the Cliffs of Moher, it's a very long way to go just for the day. If it's a case of you really wanting to go, you'd be better of staying in the west for the time you are here.
Two sites that might be able to make up your mind about whether to stay east for west;
West Coast; www.wildatlanticway.com/home
East Coast; www.irelandsancienteast.com/
If you do decide to stay in Dublin there are plenty of places / things to do / day trips (not as far as COM);
Casino in Marino (in the suburbs)
Kilaminham Gaol (would need to book in advance)
Glasnevin Cemetery (www.glasnevintrust.ie) to tie in with Kilamainham. The Botanic Garden is next door to the Cemetery and can walk from one to the other.
St. Patrick's / Christchurch Cathedrals (sometimes have afternoon and evening concerts)
St Michan's Church (have mummies)
Trinity College / Tour / Book of Kells
Hugh Lane Gallery, Parnell Square
Museums in Dublin - www.museum.ie/Home
Irish Whiskey Museum
Viking Splash Tour
Pat Liddy's Walking Tour
Rent a bike in the Phoenix Park (zoo is also here)
Tenement Museum, 14 Henrietta Street
EPIC Museum (Irish Immigration)
Jeanie Johnson Famine Ship
Croke Park and Museum - where GAA sports are played and you can also walk part of the roof
National Concert Hall, Earlsfort Terrace (have lunchtime and evening performances)
Abbey / Peacock Theatre
Bewleys Café Theatre (currently in Powerscourt Town House, top floor)
Smock Alley Theatre
Project Arts Centre
Samuel Beckett Theatre in Trinity College
Seán O'Casey Theatre
Pavilion Theatre, Dún Laoghaire
Viking Theatre (above Connolly's Pub), Clontarf (can get the 130 bus from Lower Abbey Street).
IFI Cinema in Temple Bar (also has a café / bar)
Trips outside of Dublin;
Newgrange (info will be on Heritage Ireland site)
Howth Summit / Village / Harbour - you can get the 31 bus from Lower Abbey Street which will leave you near enough to the Summit which has a great view of Dublin Bay and then come back down to the Harbour (restaurants / pubs). Alternatively, you can get the DART (train) which will leave you at the Harbour.
Malahide Village and Castle - you can get the 32 from the same stop as the 31 or the DART. There are also plenty of restaurants to choose from here too.
Dalkey & Castle - you can get the DART to here
Dún Laoghaire - you can get the DART to here too
Enniskerry in County Wicklow (you can get the 44 bus with Dublin Bus - timetables on www.dublinbus.ie)
Glendalough, County Wicklow
Thank you so much these are great
4 nights means only 3 full days. I’d stay in Dublin and plan one day trip.
Day1 arrival-what time/from where?
Day3 day trip
Day5 depart what time from/to where?
If I understand your plans correctly.
We did a day trip to the Giant’s Causeway, enjoyed it, but it was a long day.Edited: 17 February 2018, 07:58