Funfields really is a great park for families. All their rides and slides are all 'family-thrill level friendly' (if that makes sense). As a melbournian I have visited Luna Park, Adventure Park in Geelong and Funfields many times. Out of the three I would recommend FF hands down as Melbourne's flagship park. The biggest draw at the park, sans the toboganns, is the large grassed grounds, trees to sit under and covered seating areas. Heaps of people bring in large eskies, use the barbeques and have a picnic. It's what makes the park unique; Funfields feels like a large local park with rides/slides, vs. rides/slides with a grassed/shade area. It's unfortunate that park doesn't have much for thrill seekers, but my bet is this will change in the coming years (starting with the tornado wave).
@Jobe The park doesn't have much room for expansion. @Gazza I like your idea of removing the go karts. Removing the gokarts will free up a nice plot of flat land. I will not miss them, but the majority will; they are always super popular.
Red = (what I think) might be available expansion area.The hill gets very steep up towards the end of the land....probably unusable, unless they spend major money on earthworks.
Orange = The dream would be to see a terrain hugging coaster utilize that steep land.
Yellow = Existing picnic, grass grounds and shade area.
Cross hatch light blue = They could use this hill and build a coaster, or multiple waterslides that fly over the toboggans.
Purple = This is where the new toddlers water play area is going. http://www.funfields.com.au/rides/birdy-cove-waterplay
Green = Overflow carpark, which is definitely needed in the summer. I've seen this fill up completely before.