Hi Amelie. I have both those on my block I also have
Brachychiton acerifolia:: Illawarra Flame Tree
Xanthostemon chrysanthus:: Golden Penda
Buchinghania celsisima:: Ivory Curl Tree
Stenocarpus sinuatus:: Firewheel tree
Hymenosporum flavum:: Native Frangipani
Cassia fistula :: Golden Showers
Flindersia brayleyna:: Queensland Maple
I have lots more but they are screening trees.
Here are some I have grown in my last garden

Lagerstonia indica :: Crepe Myrtle
Tabebuia, Yellow and Pink :: Trumpet Tree
Tibouchina granulosa::
Bauhinia
Grevillea's so many

All of the above flower, and there are so many they are all my favourites. I also have a Liquidamber only small yet that I planted for the Autumn leaves, Its hard to make a choice some of those will be too tall but look them up as sometimes they dont grow to that hight in suburbia.

The Qld Maple and the Trumpet trees grow fast hope this helps a little and good luck with your choice. Cheers...MM

Have you thought about tibouchina alstonville. Pretty fast growing, beautiful purple flowers and hardy as can be. I love them.

Thanks a lot for the suggestions.
Mistymorn, I love most of the trees on your list. I was pootling round the yard this morning and noticed that one of my penda's has some little buds about to open. I thought of pendas as a tall screen. I just love those flowers!
I have a Queensland maple in the back yard and it's done well. When recommending this tree to a neighbour the other day, I realised that I don't know if I've ever seen a mature one??? Will do some research on that too.
I will check out the tibouchina - isn't there one with both dark pink and pale pink flowers? I've seen then round the neighbourhood.
Thanks again for the ideas.

I have never seen one, but that does not mean there isn't one
You would not be getting it mixed up with one of the Bauhinia's would you
As there are plenty around Brisbane, they call it the Orchid Tree....MM

There is a Tibouchina with both colour flowers at the same time, I can't remember its name, I think its Tibouchina Noelene, but not sure. It doesn't seem to do as well as Alstonville (the big purple one) and I don't think they grow as big. You don't seem to see them around much anymore. There is another smaller one to about 1 - 1.5m called Elsa that has whitish flowers and purple stamens. I have one, the flowers are pretty but the bush can be straggly.
All of Mistymorn's suggestions are good, depends if you want deciduous or not. Another nice one is Pink Cassia and I love Golden Pendas.
For a screening plant have you thought of Murraya (mock orange) - beautiful scent.

Thanks Mistymorn. Misty I know the bauhinia. I have an orange one and the lady a couple of doors up has the pink one - it's leaves head my way at this time of the year - (must send the guy next door completely mad - he hates leaves).
Goldhills, I think you are right about Noelene. Old fashioned plant I think. I have lots of mock orange already - have weedy tendencies I believe (not noticed in my garden), but the perfume is gorgeous. They don't seem to do too well on my soil.
I'm going evergreen for the feature tree - though it will be in the north facing front yard - I hate the view of the road and other houses. I may go for a grevillea hedge (will pop over to the natives forum later).
... I may change my mind a hundred times, then plant something and change my mind again ... too much choice - that's the problem.

If screening is the top priority I would strongly recommend Syzygium jambos. Reasonably fast growing dense to ground tree to about Mango size with glossy largish leaves and reddish new growth. Flowers lemon followed by Large white fruits. The flowers and fruits are "quietly" beautiful but the form and shape of the tree is its best attribute. Can be pruned underneath if you want to open up the lower level. Robyn

How about michelia figo? It's evergreen, can be grown as a feature tree or probably pruned as a screening hedge, and has those beautifully scented flowers in flushes throughout the year. I've seen only the port-wine scented variety, but others have spoken of the banana-scented one. I guess the trick is to buy it in flower or take cuttings from a known cultivar.

Ooohhh more ideas, thanks so much!

Cestrum, My father had a Port-wine magnolia in his front yard all my life.. it is a wonderful plant.. the scent is magical. It was only on reading your post that I was reminded of this plant.. There will soon be one in my front yard.. thank you!

You're most welcome, Saletta. It is a lovely plant, and its small glossy leaves allow it to be clipped and kept as a tub specimen for many years, looking a little like a potted weeping fig but with scented flowers. So there's probably a space for it in most gardens--as feature tree, hedge or tub plant.

I thought i'd add another couple of choices if you are still needing them!
Gordonia axillaris 'Yunnanense' or Silk Screen - an absolute stunner - looks like a magnolia x camellia - I am told it would do well up in Brisbane. Excellent screening, fastish grower and evergreen.
Michelia doltsopa - again I am told they would be happy in Bris. evergreen, scented flower, screening, beautiful.Both would requre watering until established.
cheers!

A tree that will grow fast to the right size and looks very graceful is murraya koenigii (curry leaf tree), but it doesn't have any significant flowers. Leaves are used as herbs in asian cooking.

the tibouchina or even a port wine magnolia.They are two really beautiful trees that I have seen growing in Qld.
I think you are going to have a hard time pruning the list down.