I would do Watsons Bay ferry trip as an optional activity late on the Saturday morning, with view to having lunch at Watsons Bay hotel, or those wanting something more casual can get take out fish and chips from Doyles (the takeaway at the back is more popular than the expensive sit down) and sit in park. Then a walk across the road up to the gap for views.
Those wanting to stretch legs could then get bus to Bondi (its 10 mins away), grab an icre cream or coffee then do the cliff top walk from Bondi to Bronte (20 mins) or continue to Coogee (about an hour), then bus back to the city.
That gives time to clean up before dinner. Watsons Bay is a pain to get home from at night.
If group choose a dinner venue in city say near the rocks or circular quay then visitors can get some night views of the harbour bridge and opera house after dinner. But then there is also king st wharf area, chinatown or surry hills with lots of food options good for groups. I would need to know likely head count and opinion on food types and budget to suggest best venues.
Other day activities can be a free rocks walking tour, then a walk across harbour bridge (or train to milsons point then walk back across bridge visit observatory then a pub for a tipple).
Or anyone feeling less like walking could always do high coffee at the intercontinental or high tea at sheraton in the park or qvb or swisotel.