One of my favourite dresses in the game and the second last Princess Leia dress to acquire, I found the off pieces really hard to collect. The boots and gloves were the last two pieces I needed. The whole outfit took two months to finish, recently purchasing the gloves from the AH. Unfortunately, there are no pant options that suit this type of dress that seamlessly. I’d be a lot happier if you could just hide the pant option given the current choices in-game but since that’s not possible, your choices will be limited for transmog purposes.

Shoulder: Lightning Infused Mantle
Chest: Robes of the Guardian Saint
Waist: Ruthless Gladiator’s Cord of Accuracy
Legs: Ancestral Woollies
Hands: Arachnidian Gloves
Feet: Arachnidian Footpads
Main hand: The Undeath Carrier
Wand: Wand of Prismatic Focus

Alternate Options
Head: Cowl of Benevolence
Weapon: Hammer of the Astral Plane
Off hand: Eerie Stable Lantern