ha ha, parallel lives - we had the same discussion (and outcome) after our Bonfire Night party. He played Firestarter, I had a visit from the DHL man the following week
anyway, flattery will get you everywhere (plus I have an undeniable soft spot for you bc of your choice of spouse) but be warned that I am now going to waffle.
Those bags would probably tick all of your boxes but they - particularly the Ramalamas, not so much the Tuttos - might look a bit wrong when you actually touch down. Just a bit too heavy, too leathery. I'm not all about matching the bag to the shoes but I do think that brown/ black leather bags look at odds with flip flops, flat strappies etc which is most likely what you'll be wearing, even at that time of year, in laid back Qld. If you're going for leather, then metallics like [http://www.happybags.co.uk/category-177/820.html this one]] work better I think.
There's also these bags = both in the sale and both casual/ beachy enough to work in warmer climes and not look at odds. Admittedly no top zip though ... For that, there's this or this If they don;t have enough compartments, I generally tend to buy a couple of zippered nylon washbag/ make up bag thingys in different colours/ designs and assign each one to a different dc so that they're easy to identify and grab, and easily portable if you need to take one to the loo or whatever.
Since your dds are also at a reasonable age, I'd also get them each a bag of their own to carry their own activities & bits and bobs. If they're anything like my oldest 2, the taking out and putting in of their things will constitute an activity in itself! Have you seen clippykit? Girls love them and filling the pockets is in itself an on-board activity. Start getting busy with the scissors now and you could have a whole stash of pics in your carry-on so that they can change their designs over and over again ...
hope that's a bit helpful lovely .. will keep looking out for bags for you in the meantime. I've ordered the plum Phoenix, we must compare notes when they arrive!