Just getting your PM now so I hope it's not too late.
You're in for a treat as the weather is supposed to be great tomorrow. All of the above are good suggestions but some others worth considering are;
St. Stephens Green - a small park at the top of Grafton Street opposite the shopping centre. Very, very popular at lunchtime when there is just a hint of sun.
Iveagh Gardens - if the above is too busy head here. It's a walled garden and not too many people know about it but great for photos.
Christ Church Cathedral - tripods are allowed inside. Stunning church.
Dublin Castle - well worth a visit. There is a sand sculpture exhibition on at the moment in the courtyard.
National Museum of Ireland - get off at the Museum stop on the luas red line. IMMA (Irish Museum of Modern Art), the War Memorial Gardens and Kilmainham Gaol are close by. Kilmainham Gaol is by guided tour only but you are allowed to wander around the cells at the end of the tour without the guide.
To be honest, you won't have enough time to visit everything so just enjoy yourself and come back over another time to visit the rest.
Have a look at
Dublin Tourist website for details of where each place is located.
One other thing, the tourist office is located at Suffolk Street. It's a converted church.