Mini Monkey HiLo Highchair
Find highchair retailers locally and online in the Bub Hub Australian Pregnancy & Parenting Directory.
The HiLo chair is expensive, but that's its only down-side.
I like the clean, functional design. It is very easy to get your child in and out. The tray is a good size and has a clear cover which easily snaps off for cleaning. It also has a built-in cup holder.
Our daughter is 3 and still fits in it easily - it can apparently be used up until 6 years of age. You can adjust it down to the "low" position when they get older and are tall enough not to need a high chair.
I recommend the HiLo chair but at $400 will not suit everyone.