The Guinness tour is good, and the bar at the top of the tour is great - fab views of the city, and the best pint in Dublin.
FX Buckley (a local butchers) have a few restaurants dotted about, and serve up really good steaks.
If you want lively bars, the city centre/Temple Bar have loads but always packed.
The cellar bar in the Merrion hotel is great for a quieter drink, if that's your preference.