Did some blending on two of the royal clothes, definitely not done yet. I decided to add an ermine.... thing. Sash? I don't know what to call it. Anyone, I decided to add an ermine thing on one of the royal clothes to make it look more medieval and more fancy.
Those long ermine capes are called mantles.
I dug out my Costume Design book for this, so:
The clothing that GRRM describes varies since he's taking smatterings from everywhere, but it seems to be more Early Gothic (1200-1350) than Late Gothic (1350-1450). But there's also a bunch of Byzantine/Romanesque early Medieval stuff and, especially in the Free Cities and the bravo clothing, Renaissance, with it's big-ass leg-o-mutton sleeves and bright colors and slashing. This seems to put it mostly in the timeframe of what GRRM has said he was going for, which is to say, War of the Roses and Hundred Years War -- transition from High Medieval to Renaissance.
To make Dornish dress more Renaissance-y and silk-y without relying directly on Turkishgfx or anything, look into men's houppelande's with high, stiff collars, a mix of bobbed hair, straight Byzantine page-boy hair, and bowl cuts. Poor folk would be wearing fillets and coifs under their hats, but the chaperon with a long-ass liripipe going way down to their belt-loop was style-du-jour. Also, jeweled bandoliers.