If you're ever wandering around town and want a nice, relaxed tea or coffee, I'd suggest considering 'Joy of Cha' on East Essex St in Temple Bar. As the name suggests, it's more of a tea place than a coffee house - but the coffee is still quite nice.
They have a wide range of teas. My favourite so far is pear & cinnamon. Mmmm. And all of their teas are available for purchase in case you like one and decide you want to make some at home.
On a Sunday morning, when the weather is nice, sitting outside and reading is very, very pleasant. OK, that's true in general actually, but having nice tea and coffee available certainly adds to the experience.