Couple of interesting places that i like.... if you are near Brisbane
Fort Lytton Brisbane
The old gun emplacements out at fort Lytton are pretty good open on Sundays and they do tours of the place during the day...if you get down there on the 22nd of April they will be firing the cannons a few times in reenactments during the day....and its free
Queensland Maritime Museum has a a warship and a lighthouse boat that you can go inside.
Nuggs one of the Brisbane based members arranged a tour of Gateway Bridge a few years back,
Rail Workshops in Ipswitch