Port Elizabeth's sightseeing is compact and walkable. The old town hill above the harbour — Donkin Street, the Reserve, Fort Frederick — can be covered on foot in a morning, and the Route 67 public art trail links it all the way down to the waterfront. The city punches above its weight for a place this size: a genuinely moving apartheid-era museum, one of the oldest cricket grounds in Africa, and a handful of monuments with surprisingly good stories behind them.
Don't try to cram too much in. A day of city sightseeing followed by a day at Addo is the natural rhythm here. The art museum is small but worth a look on a hot afternoon, and Bayworld keeps children occupied for hours. The real magic of PE is that you're never far from a beach or a wildlife reserve — city culture is a bonus, not the point.