Lucky enough to have family still living in the area, I felt right at home in Dublin from the moment I arrived. That feeling is not exclusive to those of Irish decent. The Irish people are some of the most welcoming you'll find anywhere, so prepare to make a lot of new friends -- mostly over a pint of Guinness. While the food might not be anything to write home about, the drinks and company cannot be beat.
EXPLORE
Old Library at Trinity College is the largest library in Ireland and dates back to 1592. While you might be visiting Trinity College to see the Book of Kells, definitely continue on to the Old Library, you won't regret it.
Hugh Lane Museum is completely free and open everyday except Mondays. Small enough to do quickly, the museum has exhibition, events, and nice cafe. One thing not to miss -- Francis Bacon's studio, which was moved piece by 7,000 piece from London to Dublin. Everything from paint brushes to dust (!) was entirely re-set as Bacon left it.
Guinness Storehouse and Gravity Bar is a no-brainer. Wander through the facilities on your own or join a tour for a more in-depth visit. Do not leave without a pint of Guinness at the Gravity Bar on the top level -- it has the "perfect pour" and 360 degree views of the city.
Cork and Blarney Castle is an awesome day trip if you have the time. A 3 hour train ride from Dublin, Cork is known to its residents as "the real capital" and is a lovely walkable town. Not far outside of Cork is Blarney Castle and Estate -- home to the Blarney Stone of course. An afternoon spent exploring the gardens and ancient castle ruins is a day well-spent.
SHOP
Drury Street is full of killer vintage shops, favorites include Retro, Harlequin, Jenny Vander, Om Diva, Beaux Bows, and Carousel. Want even more vintage? Check out the stores just a couple blocks north on Fownes Street.
George Street Arcade is right near Drury street, so don't miss your opportunity to hit both. Inside the covered shopping lane, one of Europe's oldest, you'll find boutiques, eclectic shops, food stalls, and more.
EAT
Stag's Head is one of the oldest pubs in Dublin, dating back to 1770. With great atmosphere, cask-aged whiskey, good pub food, and colorful local characters, Stag's Head is a perfect anti-Temple Bar spot.
O'Neill's Bar and Restaurant is your traditional Irish pub and grill, but with all kinds of hidden little seating areas tucked away in it's multi-level floorplan. If it's warm enough, the rooftop beer garden is the best place to be for an evening filled with drinks and good company.
Mulligan's is another great pub (This "EAT" section should probably be called "DRINK"...) with a storied past. With over 200 years of history, it's hosted everyone from Judy Garland to JFK. Park yourself at the bar, catch a soccer game, and enjoy a Guinness (or 5).
STAY
Number 31 is the next best thing if you don't have any quirky amazing Irish relatives to stay with, like I did. This downtown house-hotel is more bed-and-breakfast than hotel. Complete with a little garden between the two buildings, Number 31 is a supposed favorite among Dublin insiders and creatives.