I would highly suggest getting a ticket for an open top bus as the city is quite big and walking around it will take ages, plus the bus takes you to all of the top attractions and you can see the city while sitting down. There is so much history in Dublin and going on an open top bus is the perfect way to learn about it either on the recording or from the live guide.
We stayed at the Academy Plaza Hotel which is located perfectly just round the corner from O'Connell Street which is a busy main road in Dublin. The rooms aren't huge but the beds are comfortable and easy to move around in.
The Archaelogy and History Museum was brilliant, when I was there, there was some exhibits on the Romans, vikings and things that had been found on farmland in Ireland in a bog. The bog bit doesn't sound great but it was seriously fascinating, they found people in the bog from hundreds of years and they still had skin and hair. I would set aside a good couple of hours if you are going to do the museum as it's a lot bigger than it looks on the outside.
Hard Rock Cafe was amazing! It's over 2 floors, the cocktails are amazing, the side plates are awesome sharers and the memorabilia is mind blowing. If you buy one of their cocktail glasses with your cocktail, you will get it cheaper than buying it on it's own in the gift shop.
Guinness Storehouse is an absolute must, it will take half a day to get round it all but it is worth it. You go through the process of how Guinness is made from start to finish getting loads of facts and see the equipment that has been used at every stage. You go through an exhibit which is all about the advertising that they have used through the years. There is also a bar where you can learn to pull the perfect pint and then you get to drink it. There is a tasting session where they take you through some of the flavours that make up Guinness and then you get a tiny shot glass sized Guinness glass with your sample. At the end of the tour, you are at the top of the building in the 360 degree bar where the walls are all glass and you can see for miles over Dublin. You also get a free pint or a soft drink at the top to enjoy the view.
Madigan's on O'Connell Street is a great little bar that does yummy food and has live music. They do a fantastic breakfast with is about 10 euros but it is huge portion and super yummy.
I found the Dingle Whiskey Bar completely by accident, we got off the bus randomly to have a look around and saw it so decided to go in. It is a bit dark and feels like a little hidey hole but
It can be quite expensive to buy anything in Dublin, I found that even with the exchange rate, it was quite expensive. From bags a crisps, to drinks in a pub, it can be expensive so make sure you save up a bit of extra spending money.
Make sure that you walk around as well, the streets are full of so much history and the architecture is out of this world.