We took this 3 day tour in May 2019 pre-COVID just before taking a 14 day tour in The Republic of Ireland. The tour guide and driver was Stephanie who was excellent both in her driving of the narrow lanes and knowledge of the tour area. The tour group were mostly Canadian (8 of us) plus one from France. We were based in Bangor for the two nights at a BnB called Shelleven House.
The tour started in Dublin with the first day concentrating on Belfast (Titanic docks, and infamous sites such as the Peace Wall, protest Gate, army towers, etc.). On the second day we took the Causeway Coastal route (including some very narrow lanes for even a small tour bus) along the Atrium Coast to the Giants Causeway and back. The third day took us back to Dublin. Along the way we visited Mount Stewart (the ancestral home of the Marquis of Londonderry who oversaw the Treaty of Versailles conference), the ruins of Grey Abbey, Carrickfergus Castle (which was associated with William of Orange), Ballycastle, Stuart House and Down PatricK (where apparently St Patrick is buried). Included were Game of Thrones sites at Glengoy, Ballintoy, the Dark Arches, and Castleward.
For a quick tour of Northern Ireland it was very good, and I would recommend it for a quick introduction.