Ateed's tourism manager Jason Hill said of up to 1000 delegates and participants about 290 were travel buyers from overseas.
"It's about having the world on your doorstep and showing them what we've got," Hill said.
"We still have the challenge of being seen as a big gateway. It's through the travel trade and industry that we influence the length of stay."
Hill said buyers responsible for packaging holidays were coming from Australia, the United States, China, Japan and Britain.
"It's about influencing the influencers and getting them to understand there's enough to do in Auckland to justify staying here another night or two."
He said it was hard to forecast the long-term benefit of hosting TRENZ but delegates at the conference in Queenstown last year spend about $1.4 million.
Hill said Auckland had potential to appeal more to Asian travel buyers, including the fast-growing Chinese market.
While Chinese tourists were not going to come to New Zealand for a city experience, shopping, branded hotels and quality restaurants gave them "a sense of comfort".
He said Ateed staff travelled to China three times a year to talk to travel buyers, although Australia remained the biggest market.
Just on 700,000 Australians travel through Auckland a year and a deal between Flight Centre and Ateed has resulted in the travel agency in Australia promoting extra days in Auckland for wine, the Gulf islands, adventure sports and animal-watching. It was hoped 20,000 more Australians a year could be attracted to stay on for extra days.
Flight Centre's general manager of marketing, Colin Bowman, said Auckland Plus packages had been launched in Australia last year.
"Both of us [are] looking for the same sort of outcome, we're working more co-operatively, not only our marketing effort but also exposure to Auckland and its surrounds."
New Zealand remained a popular destination for Australians.
Auckland City's chief economist Geoff Cooper said while tourism made up just 4 per cent of the region's economic activity, it was an important foreign exchange earner with potential to grow more in high-value, boutique areas.