Ah, Dublin. As the country's capital, it's probably the first place you think of when you think of Ireland. And don't get me wrong — Dublin is beautiful and so much fun, but if you're visiting Ireland, don't spend more than a day here, two days tops. Why? It's very similar to most big European cities, and after you do the obvious highlights like take a tour of the Guinness Storehouse, grab a drink in Temple Bar, and walk down Grafton Street and through St Stephen's Green, you're basically done.
Since you'll probably fly into Dublin airport, a good strategy is to take a nap at your hotel after you land in the morning, head out and see the city for the rest of the day, get a good night's sleep, and then leave the city the next morning or afternoon.