Below is a copy of a previous post which covers most bases.
Gruel, Dame Street - Good Home Cooking, Modest Surroundings
Dunne & Crescenzi, South Frederick St - Italian anti pasti, panini, pasta etc
Yamamori Noodles, Georges St-Decent sushi and good noodle dishes
The Exchequer Gastro Pub, Excehquer St - All the usual gastropub staples
2. Mid Level Lunch/Dinner:
Pichet, Trinity Street - Contemporary bistro - very popular
Winding Stair, Ormonde Quay-Modern Irish Cooking, great wine list
La Maison, Castlemarket St - Classic French bistro cooking in bright, modern room
L'Gueleuton, Fade St - French style brasserie with an Irish twist
Pig's Ear, Nassau St- Good quality Irish cooking with nice views of Trinity College
3. High End:
Thorntons, St. Stephens Green - my personal favourite in Dublin. Great lunch deal at the moment for stellar cooking. 1 Michelin Star but tipped to win back second.
Chapter One, Parnell Square - Very popular, high end Irish cooking and service. 1 Michelin Star.
Restaurant Patrick Guilbaud, Merrion Hotel. Currently Ireland's only 2 Michelin Star. Sublime service, very good food, very expensive.
One Pico, Schoolhouse Lane. So far overlooked by Michelin but excellent lunch deal for the standard of food and service.
Pearl Brasserie, Merrion St. Stunning room with great service and excellent quality cooking.
I hope this helps. Enjoy your trip and please let us know how you get on.