Considering their native range is over a large part of a huge continent, some live on or near sand, some live in woodlands, some live in towns.... That said they also have the opportunity to move to a different terrain of they choose.
http://tinyurl.com/m6hw2m9
I tried a setup with half sand and didn't like it. It never stayed where it should and was just a mess.
I don't like sand for a few reasons. It's dusty, it doesn't hold a burrow so it's almost useless for digging, it's like a litter box hygienically and its doesn't give the lizard a stable surface to walk around on.
I use a bioactive substrate and I encourage people looking at sand or other loose substrates to check into that method. It's a good option if your looking to add enrichment for them (such as digging).
For newer keepers solid flooring can be much easier and safer to learn on.