I regularly walk through Frick Park. The River View Trail loop is a nice ~1 mile hike, with a giant hill to climb (unless you know the shortcut along the dog park, in which it's just a moderate hill).
Every time I wander off the River View Trail loop, I get lost for hours. If you end up at the bottom of the hill near Swissvale, you're going to have a grueling uphill hike to get back home! This park is a ginormous city park, sometimes you'll find yourself in areas where you an't hear the cars, or even other people. There's also a decent quantity of open space and an off leash dog park. Plenty for everyone to enjoy.