Great area, if possible I would remove most of the grass and put down pavers, decking or combine the both for a stylish look, built in seating, lush plants , could look fabulous.

Your garden has great bones with the existing plantings, it just lacks accent interest to take it from nice to wow.

NZ Rock Lily (Arthropodium)

would look great in the part where grass won't grow. It likes shade and the dry once established. Will look good with lily pilly's or is that photinia?

Not a common nursery plant but you can get them shipped from Australian Plants Online for a reasonable price.

While passionfruit is a fast grower it's not the best choice as a canopy vine as it tends to die back and need pruning periodically. Try a pandorea instead. They are natives that are very easy going. Full sun to part shade with many beautiful flower variations. If you are going for the rock lily then pandorea snow bells will work beautifully with it. It's lightly fragrant and very heavy on the flowers during spring and summer. It's a wonderful native alternative to wisteria. This vine is also fast growing so it can fill that space beautifully. It's a cracker of a plant and Bunnings have them in their Upstarts range for $3.50 per vine. Don't worry about the small size they double their size practically every week.

I think what you also need there is some colour. And I've got just the plant for you, Coral Bells (Heuchera) is a temperate plant that loves shade and comes in many different colours. My personal favourites are the corals. These are lovely mounding ground covers that you can plant as specimen items to add interest to the garden. They are often added to Japanese gardens for their colour. I would tuck 2 or 3 of these bright babies around the rock lilies and then place large bush rock in strategic locations to create a bit more of a landscape feel to the area.

Thanks heaps for all of that detailed plant info! Some great ideas! I especially like the idea of the pandora instead of the passionfruit. Thanks!