Desirable areas could mean different things
here's a tiny sample:
Foxrock, Howth, Killiney, Dalkey
Good train connection to city centre
(On the DART or Luas lines):
Dun Laoghaire, Dundrum, Blackrock, Castleknock, Ranelagh
By the sea
Sandymount, Blackrock, Killiney
Quality of housing
Glenageary, Foxrock, Killiney, Rathmines, Drummcondra
Ranelagh, Portobello, Temple Bar
My favourite would be Ranelagh as it has most of the above (except the sea) and you can walk there from the city centre or catch the luas.
You need a large budget. Even half a million $ would only get you a small 2 bedroom house in these areas.