For more than 60 years, Currumbin Wildlife Sanctuary has been introducing locals and visitors alike to Australia's amazing flora and fauna. This is a no-frills, un-flashy kind of place where the highlight is getting close to nature (very close in some cases -- like being 10 feet from a snake during the snake show, if you're in the front row!) You can pat kangaroos, hold a giant stick insect, and take part in the raptor show, if you're lucky and don't mind holding dead mice for the hawk's dinner...
It's an all-outdoor location, so take plenty of water and sunscreen. And if anyone in your party has little legs, be prepared to carry them; there's lots of walking to be done, and much of it is uphill. There are food outlets at the sanctuary, but they're the hot-dog-and-ice-cream-type, so take your own lunch if you want something a bit healthier.
A full day at Currumbin will be a highlight of your visit, but plan something a little less strenuous the day before or the day after -- all that fresh air and fun will wear you out!