Here are my all-time favourite places:
Howth on a sunny day
The airport - because that usually means you are going away!!! (unless you work there, liky my boyfriend, poor fella)
Iveagh Gardens near Harcourt St
War Memorial Gardens in Kilmainham
The roads around Kilmainham are lovely to walk around on a nice evening
Henry St when I have money to spend!!!
Heuston Train Station because that's where I used to take trips to Galway, which is another favourite place of mine