A difficult thing for vendors, this sponsorship of conferences and events. Ideally you want those present to go away and remember that you sponsored the conference, and to have more knowledge of your products. One way to do this is with product literature. Another way is with branded gifts. A question with gifts is if you offer them to everyone (including your potential customers) or have a lusted-after gift which you offer as a prize.
All choices are problematic. Which is why vendors so often waste their money.
But here's a few ideas:
Invent something everyone wants. In my field of data communications: a tape measure in Rack Units.
Supply something everyone didn't pack. In Seattle, an umbrella. In Adelaide, a hat. A purpose-made map of the town showing the geek highlights. Tickets to a local production of one of Terry Pratchett's Discworld books.
Play to your strengths. When in Adelaide, give wine or food. Pack it so it will travel, label the package so that people can fill in their customs and quarantine forms correctly.
Explain your product. Forget the brochures. Take a room near the conference, set a time after the main events, offer drinks and nibbles, and get one of your presentable technical staff to explain how the thing works. Have the product on hand. Not just one, but several, with at least one disassembled (use clear plastic covers if you must). If it's cheap then raffle one off to the attendees. Get your sales staff to mingle and work their magic.