Gday Dave some things I can quickly think of....
1.Day exploring the city CBD-nice way to start is coffee and breakie at the barrack street jetty and use the free public city transport to get around.Plenty of cafes and pubs to choose for lunch etc.WA museum and art gallery, Horizons and Sci-tech are close at hand and plenty of shops to check out.
2.Perth Zoo, one of my favourite places , its a good days outing.Theres a few more wildlife parks near Perth
3.Fremantle like the city is a good days exploring, the maritime museum is pretty good with views of the entrance of the harbour.
4.Swan river cruise- maybe integrate a visit to freo by catching a ferry from the city
5.Rottnest island -you can either catch a ferry from freo or hillarys boat harbour {30 mins north of perth and has some nice cafes/shops and sheltered beaches}.Haven't been to Rotto for ages but had a ball when I did go , kids will love the resident Quokkas {dwarf like wallabies}.
6.Penquin island - small island just of the coast near Rockingham and not far from Garden Island that serves as a base for the RAN
7.Adventure world -theme park, not to the same standard as the big ones in Queensland but still not bad {next door to it there is a bungee jumping venue}
8.Swan valley spring festival- think around that time the wineries in the swan valley have a series of art/wine and music festivals
9.Kings Park- top lookout views of the city and the swan river, nice walkways and a excellent place for a picnic.
10.Perth Observatory-has tours on Sunday afternoons {start at 3pm i think}, also its nice driving up that way to.
http://www.westernaustralia.com/en/
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