The Guiness storehouse is fine for a visit. You wont see the actual brewery though, not since the early '00’s. Price of entry gets you a ticket for a pint on the top floor which has a nice view of the city. You can often find some teetotalers who are willing to give up their tickets (free beer!).
I’d recommend taking the bus to St. James Gate. In the summer there’s usually a hop-on, hop-off bus tour running. Then you dont have to worry about driving.
Edited for typos
