There are many options in the area for resting your head. Below are a few to suit different budgets.

Generator hostel
($) A budget, clean & modern option in the centre of Smithfield Square. This is an upmarket hostel with a bar on the ground floor. Other locations across Europe lead me to believe they are doing something right. Favoured by an 18-26 year old crowd but open to all. A tram station is 10 seconds walk from the hostel, on Smithfield Square, so it is convenient to get around the city.
Maldron Hotel
($$)a business hotel with few amenities or facilities, but this means you get to stay in very comfortable, stylish surroundings if you can cope without some facilities - a gym, swimming pool or on-site restaurant. Located at the top of Smithfield Square, opposite the Cobblestone Pub & 60 second walk from Seven Social Restaurant.
Ashling hotel
($$$) newly renovated, this is a plush business hotel. Located 1-2 minute walk along the tram track from Seven Social. You are right beside phoenix park if staying here. A tram runs outside and Heuston train station is directly across the road to link you up to the rest of the country.