I would recommend:
Option #1: Check out the Strip District
http://stripdistrictneighbors.com/
- Lots of little places to grab a bite. Gaucho is ranked in the top 10 of places you have to eat in 2016 according to Yelp. And that was for all of the USA.
http://eatgaucho.com/ Lines can be ridiculous. Best times to eat are 11-12 or 2:00-5:00.
- The Heinz History Center is at the beginning of the strip. It's a pretty kick ass place. When I last went, last year, they had a whole Pittsburgh sports thing with tons of Lemieux game worn stuff. It's actually still there according to their website. Heinz History Center to Gaucho is like a 10 minute walk. Just one street up and a few blocks. Very safe.
Option #2: Check out Mt Washington
Mostly just so you can ride the incline up and then check out the view. There are some good restaurants up there, but I would recommend going downtown into Option 3 for food. Pittsburgh = foodie nation right now.
https://www.visitpittsburgh.com/about-pittsburgh/neighborhoods/mt-washington/
Option #3: Cultural District
My favorite restaurants in Pittsburgh. Proper (brick oven pizza joint), Meat & Potatoes, Sienna Mercato (has a 3rd floor beautiful bar with an overlook).
Honestly it's my favorite part of the city. What I would do is get reservations at Meat and Potatoes or Proper, then after go to Sienna Mercato (all walkable) and go up to floor #3 to sit down, have a beverage, and take it in.
This is Sienna's Beer Garden. You can have a drink (even non-alcoholic if you aren't a drinker) and either sit at the bar, walk around, or whatever. Not really a formal seated atmosphere.