I have done a lot of running in
I’ve done the Great Race and the Steelers 5k here.
The Great Race (10K at least) is nice because it’s so downhill. You are pretty much guaranteed to PR.
The Steelers 5K is alright for the novelty of finishing in Heinz Field, but I won’t do it again.
I remember them summoning all of the runners to the starting line and just as you’re warmed up and stretched, waiting for the gun to go off, the start introducing Steelers alumni who give a little speech and then sing the National Anthem while you’re muscles are getting cold. Not to mention, I feel like it’s a popular first 5K for a lot of Steeler fans, so you have a lot of problems that come with noobs (lining up too far in the front so you spend the entire first mile weaving in and out of people who you need to pass).
The Indiana Road Runners Club puts on a few great races every year in Indiana, PA (not the State, it is about an hour east of the city). Their marathon is the cheapest you’ll find anywhere.
The City Department of Parks and Recreation (Citiparks) has a number of 5k races (usually draw 300 – 1500 people) during the summer and then hosts the Great Race (~15,000 people) in the fall.