Hi Andrew,
Try Hearsons Cove out on the Burrup peninsula when there is a full moon. Quite a few people go out there for a phenomenon called the staircase to the moon.
http://www.karrathavisitorcentre.com...e-to-the-moon/
I happened to be working up there when the last super moon appeared and the beach was packed to the brim with cars n people. Nice place to take photos.
If they are keen to stay for a while I would recommend going out in the afternoon to check out the aboriginal art that is on the same road to the beach. There's a little track about half way down that turns to the right. From memory there is some 10000 art works there. Worth a visit.
For really super clear skies this time of year a trip to Millstream National park is definitely worth the effort. Even with no scope the night sky was impressive.