Franktuary was one of my very favorite places in Pittsburgh, and the Lawrenceville location is definitely the best. The atmosphere is great, with old church pews and other repurposed objects decorating the restaurant. The staff is always super friendly and service has been exceptionally speedy every time I've been here.
The food is great, with more of a selection here than at the downtown location. All of the hot dogs are good, but be sure to ask about whatever monthly special they have going on. The Memphis is a personal favorite of mine. They also have local hot dogs and sausages and source a bunch of other ingredients from local farms. And whatever you do, get the poutine. Seriously, it's amazing.
They also have a pretty good beer selection and they can pour a mean cocktail.