I would also suggest the Toolona Creek Circuit, done clockwise
http://www.nprsr.qld.gov.au/parks/lamington/about.html#Toolona_Creek_circuit, camping at Bithongabel. You have to remember to grab water at the last creek crossing, as there is none at the campsite (There used to be a soak nearby, but not sure it exists anymore).
The advantages of this circuit, is that the first day is really nice, lots and lots of waterfalls, and not too strenuous. It's something like 13km. Bithongabel campsite if beautiful under the antarctic beeches, with great views. Then the next day is only an hour or two to get home (4km), so for someone who is doing their first walk they have a strenuous first day, sleep somewhere nice, then it's a really quick and easy walk home when all their muscles are feeling sore from the first day.
As I said, the only real downside is that you need to grab enough water at the last creek crossing for the campsite)