OConnor's Pub is one of my favorite places downtown to go for a drink. It's a few blocks north of Atlantic avenue, far enough away from the pretension that you can sit down and relax with your drink and not worry if you are dressed snazzy enough. It's also walking distance from the other bars, so it's a good place to wander to and from Atlantic.
OConnor's is a small Irish pub that always has a great band playing, usually a jam band or a blues band. They have picnic tables outside that I like to sit at because the band is then at the perfect volume that you can hear it and still talk over it. And there is usually some parking to be hand not too far from here, if you look hard enough, or street parking right in front if you arrive at the right time. Drink are reasonable, and they serve liquor and beer.