Bournemouth City Council bought the Waterfront leisure complex and IMAX site - the cinema had been voted as one of Britain's most hated buildings - in February and plans to redevelop the site.
It has put seven options forward for public consultation and will publish the responses on 20 April, before holding a cabinet meeting on 28 April.
The options include a tropical garden, modelled on the Eden Project, a family play park, a spa and a performing arts space.
Other ideas are for a water park, boutiques and bistros and an interactive arts centre and museum.
SGD chairman Annabel Downs has responded directly to the council's leader Stephen MacLoughlin about the proposals and urged him to include professional members of the society when the project goes out to design competition.
"It is about providing quality open space which allows for all sorts of different activities," Downs told HW.
"We felt that none of the options offered a really satisfactory solution for the site, so we are trying to push them further. One of the councillors is keen on a 'mini Eden', but that would be bonkers in Bournemouth."
The SGD is pushing for a public open space to be used for year-round activities including music and street theatre, outdoor exhibitions and specialised markets. It also wants a well-designed single-storey building comprising a cafe, toilets and information office.