Here are some model shots taken from WoW Model Viewer of some possible sets, all chosen for how they accentuate Shawndra's girlish figure. Enjoy, and I hope they help you as much as they are helping me!
Here is Shawndra in the Enchanted Adamantite set, wielding Corpsemaker. Missing shoulders, gloves, bracers, and helmet, this is far from complete, unless you dig further and find the Exalted Plate set (recolor). However, this is one of my favorite sets as it is sexy without being too revealing. I like the Bogslayer Gauntlets as a pretty close match for the gloves. Bracers shouldn't show, and I would hide the cloak and helm on most sets. For the shoulders, Bogslayer Pauldrons or Saltstone Shoulders are close matches. For something with a little more oomph, try Backbreaker Spaulders.
Here Shawndra is modeling the Bloodfist Plate set while holding a Drake Talon Cleaver. Now, this set has shoulder and head armor available, but I'll let you decide if it is really what you want. Shawndra's shoulders are super sexy, so I don't think I want to cover them up with some old piece of tin can. It has to be spectacular, or at least match really well. Spectacular, to me, are the Spaulders of Manifold Eyes. You could also use Pharoah's Burial Spaulders, Pauldrons of the Molten Giant, or even Pauldrons of the Souleater. There is another color set similar to this. I won't play with shoulder ideas for that one, but it is worth mentioning.
I have always loved the look of the Hyperion Plate set. There are several different recolors of what WoWhead calls the Imbued Plate set, but in my opinion this is the flashiest and most worthy of transmogrification. Many of the shoulders in the previous set match this set well. The blade she is wielding is Cataclysm's Edge.
The Vanguard Plate, otherwise known as a recolor of the Glorious Plate set, is another one that has many color versions. The shoulders that are paired with this set go fairly well, as do the Imbued Plate Pauldrons and the Lightforge Spaulders. For a little more shine, try on the Pauldrons of Edward the Odd. She is brandishing Quel'Serrar, a weapon most tanks have aspired to having at some point in their tanking career. Not sure I like this set as much as some of the others, but a post on sexy plate would be incomplete without it.
The Revenant Plate set has two different other color schemes, but this is my favorite. Shawndra picked Terokk's Nightmace and the Steelgrill Shield to go with it. For a slimmer pair of boots, try the Fen Strider's Footguards (sorry Alliance, only the Horde get these). As for shoulders, the set pieces look something like the Talonguard Epaulets, but in my opinion don't match as well. I prefer the Earthen Shoulderguards, the Rusted Bonespike Pauldrons, and the Soulforge Spaulders. An excellent match would be the Replica Warlord's Plate Shoulders, but Shawndra never attained Legionnaire, so she'll never get to have these (*cry*).
There are so many sets to transmogrify Shawndra's blah gear to, that I cannot make up my mind. Perhaps all you lurkers out there might appear to comment on your preference? I promise not to run in and yell boo, and you can re-lurk right after! I even welcome suggestions other than the ones pictured. I know I haven't seen all the options out there!