B&B? Dublin? This July? ... You should be making reservations ... yesterday. Dublin has a decent transportation system so, any place within an hour's train should be fine. My preference is staying in the West, Galway or Mayo, and taking a train for a day trip to Dublin, should I feel the need.
There is plenty to see in do in Dublin and its environs. But, I think scoring a good B&B, in the city, will be a stroke of luck. Also, I'd suggest talking to locals with respect to areas of Dublin to avoid due to crime. It's really just a large European city with all of the attendant problems.
That said, The Liffey, bridges, the Post Office, the Peterson Store, the pedestrian arcade (Grafton Street), Trinity University with the "Book of Kells" and other relics, ... lots to see and do ... Guinness, Four Courts ... Some great pubs and, if it's to your liking, tiny, tasty portions of great food in upscale eateries all for $$$. And, great Irish beef, sheep, pork, seafood in some pubs and cafes. It's all there but, to me, Ireland is an hour away. But, I have friends in The West and it's like going home.
You will enjoy Dublin though. There is more to see and do than you can accomplish in an intensive week should you decide on more than a superficial, touristy visit. If you are a "quick look see, been there done that" visitor Dublin is only a day trip. If you want to look deeper, enjoy the parks, etc. type, Dublin will keep you enthralled for a week, for sure.