Exit at South Bellefield and Fifth Avenue and walk 2 blocks to the Holiday Inn to save the 10 minute Oakland loop which gets you only 1 block closer. You can get on at Fifth Avenue and Tennyson St. for the return trip. Scheduled trip time is one hour, departures every 15 minutes to 30 minutes based on time of day, day of week. Exact fare only. The core of the AirSide building is a shopping mall, including a drug store, post office, office supplies, fast food, and many typical mall stores.
Prices are the same as at all local malls.
Note it when you leave the airport. You can continue to loop back to rental car return. In particular, allow 30 minutes extra to get to the airport. Pittsburgh drivers will almost always slow down when going through a tunnel, even when there is no other traffic. Pittsburgh drivers are usually very courteous.