Favorite thing: Make sure you walk to the end of the Busselton Jetty if you visit... It is a fairly long walk (up to 1 hour return) but it is worth doing. Or you could take the train one way, or even both ways if you don't want to walk.
Busselton is a nice town...it is easy to get around and it's a great place to spend some time.
Most people are likely to hear of the Busselton Jetty before the actual town I think...
Favorite thing: Everywhere we went in Western Australia we came across these 'black boy' plants... They are everywhere and they look fantastic...