Launched back in June to combat Covid travel concerns, the trips feature maximum groups sizes of 12.
Other features include cheaper solo room options, ensuite bathrooms, private transportation and heightened sanitation and hygiene protocols.
The four new trips take in Cuba, Madagascar, Australia and New Zealand.
G said the additions came following "positive feedback" from travellers, and "encouraging booking numbers" for 2020 and 2021 departures.
Its Travel with Confidence Plus range now features 41 trips to 28 countries, with departures through to the end of December 2021.
The trips have been most popular with travellers from the UK and Ireland, said G.
G has extended its Book with Confidence policy to cover all bookings made up to 31 December 2020, which allows travellers departing up to the end of the year to cancel and rebook up to 14 days prior to departure.
Those due to travel between 1 January 2021 and 31 December 2021, meanwhile, can cancel and rebook up to 30 days prior to departure.
The operator has also created a new in-depth Travel with Confidence FAQ for travellers and agents covering G’s efforts to make trips as safe as possible.
G’s four new trips are Australia and New Zealand Encompassed – Plus, 34 days from £7,559pp excluding flights; Highlights of Madagascar – Plus, two weeks from £1,629pp excluding flights; Cuba Rhythms: Run and Fun – Plus, eight days from £619pp excluding flights; and Cuba Explorer – Plus, nine days from £1,029pp, excluding flights.
