I visited both cities in May 2023 and will not add anything regarding architecture and history - since there are many very qualified reviews. However I would like to give an actual update of situation and how to get there.
BERAT
How to get there: Berat is very easily accessible by car or bus, just 1 hour drive from Alabania´s capital Tirana.
Sightseeing situation:
Heavily visited and crowded, but also easy to visit (but not wheelchair accessible since streets are very steep).
GIROKASTER
How to get there: Girokaster also is well accessible by car and bus from Tirana (200 km or 3,5 hours - due to newly built highway)
Sightseeing situation:
Heavily visited and crowded (lots of package tourists), not wheelchair accessible since streets are very steep.