Another thing I've seen work well is run a competition with a small prize than involves attendees visiting all of the sponsor tables. Run it at the same time as a coffee break. It's fun, folk who don't care can opt out, gets a bunch of folk some face time with sponsors.

Also, on the schwag front, do what you can to persuade the sponsors to give out useful schwag. For example I've got a stack of branded retractable sharpies that I use every day. Somebody gave out some nice branded planning poker cards one time that I still have and use. Somebody else gave some nice single-card summaries of innovation games that I kept.

The bags, frisbies, pointless brochures... not so much.