Ground Zero is the sister coffee shop to Cargo Coffee on Park St. Both make good espresso drinks and have standard pastry selections. The drip coffee is so-so, though it's nice you can order an 8oz cup as well as other sizes. Very 1950s coffee set. (Maybe not a coincidence? I'm a fan of any coffee shop like this that has the nerve to decorate in "post WWII cold war bunker".)
There is good wifi, almost always parking in the lot, and a cool renovated historic building that's shared with El Dorado Grill.
Advice: get an iced latte in the summer. It will last exactly the walk from Ground Zero down to St Vinnys for vintage/thrift shopping.