I'm going to vote I'm going to vote for Warnambool too.
It has beaches, a fantastic park with playsets, ponds etc, there is a volcano nearby where you will be able to spot emu's kangeroos and maybe a koala, it's not too far from the amazing scenery of the great ocean road, there is a rainforest with a treetop walk that combined with the great ocean road makes a nice day trip, it's a big enough town to be able to get a decent coffee. Port Fairy close and it has boats to look at.
It's a really familyfriendly destination.