First timers in PGH, looking for lunch in all the right places
A good choice would be to take the incline up to Mount Washington. From the Mon Incline, which is right next to Station Square, you could enjoy the view of the city and walk down Shiloh street to the Shiloh Grill. It's not elegant dining, but pretty good sandwich food. They also have an outdoor deck. Enjoy your stay!
2 E Station Square Dr, Pittsburgh, PA 15219
The brunch at the Grand Concourse is very popular. http://www.opentable.com/grand-concourse
I've only been once, but that's because I'm not a buffet person. It would certainly qualify as "hearty."
Grand Concourse Restaurant
100 W Station Square Dr Ste 1, Pittsburgh, PA 15219