The council would also look at options for re-purposing Forum North.
Councillor Crichton Christie said the RSA was "the best option for ratepayers, who are paying for it" because the council owned the land, it had available parking and foundation costs in the lower central city area would be higher.
Other councillors raised points about traffic congestion if the council moved into town, and said feedback from submitters showed they preferred the RSA/Forum North area.
Other councillors wanted to see what options, including "add-ons" of a hotel or conference centre, developers came back to council with.
Councillor Stuart Bell said he would "hate to exclude the option of investigating city centre, which might provide huge benefits for city centre revitalisation".
Councillor Cherry Hermon suggested the RSA and Forum North be considered as one site and moved an amendment to have the council call for expressions of interest by the private sector for the development in the central city and at the RSA/Forum North site.
The vote was split evenly, and Mayor Sheryl Mai used her casting vote in favour of the amendment.
Council CEO Rob Forlong said the council did not have any preferred sites in the central city area.
Auckland developers The Neil Group owns a block of land in the central city area which is under demolition. The developers had previously been in talks with the council over a hotel or retail precinct on the site.
Neil Group chief executive Phil Ainsworth said yesterday that the company would be interested in talking to the council about its plans for the site, bordered by Dent, John and James Sts.
WDC corporate general manager Alan Adcock said the expressions of interest document was being prepared, and would be released in July, after the Long Term Plan had been officially adopted.
Councillor Greg Martin filed a notice of motion that would bring the civic centre issue back before the council at the meeting on May 31.