Can you share the console command to change her outfit from the face-obscuring robes she wears by default? I like this idea.
Edit: For anyone interested, I have a feeling it involves a targeted additem command with the clothing you want her to wear, followed up with an equipitem command for the same itemid of clothing you gave her.
You are on the right track, but you don't need to first add the item to her inventory. Equipitem adds it and forces them to wear it. The hard part is knowing the item form id for the item you want.
1. Walk up to Orla, or any wife or character, really, and open the console with ~.
2. Click on her with your mouse to target her, and type [equipitem {item form ID}].
Personally, I like her to wear the Tavern Clothes, which is what the "Sultry Maiden" from Sheogorath's Daedric Quest wears, and also Hroki from the Silver-Blood Inn in Markarth. The Form ID for the Tavern Clothes is 000d191F. So, to get your wife dressed like a sixy barmaid, you open the console, click on her to target her, then type [equipitem 000d191F], without the brackets, of course.
Now, if only Bethesda would fix Orla so I can actually enjoy the benefit of having Orla as my wife before I finish the game.