As is the case with every tier, one looks at the 'new' stuff that's available and slobbers over the nice, bright shinies and hopes to accumulate as much of it as possible. Why? It's fun of course, and more importantly puzzing together the jigsaw puzzle of gear helps us do our job that much better.
At any rate, with things pretty well-settled in terms of stat valuation, I've settled on my 'ideal' gearset that I'm hoping to end up with now that I've obtained Shadowmourne.
For those not accustomed to the practice, I've assigned a value for each stat in terms of how much attack power it's worth (AEP) and then calculated the total value of each item. These values are based on simulators such as Kahorie's or Mr Robot. As you can see, in best in slot gear, haste is very good, second only to strength. With the Icewalker enchant on my boots, I can cap my hit (as a Draenei). For gem slots, I assigned a flat 60 AEP based on gemming for strength.
Strangely enough, the thing that immediately jumps out at me from this list is that it completely lacks expertise. Now, I'm usually a big advocate of capping stats like hit and expertise, but before you go getting all upset, here's the thinking. First, all the simulators I've used are currently rating expertise as a very poor stat, on par only with agility. I think this is mostly due to the fact that haste is so good. Haste scales extremely well, while expertise.... doesn't. Thus, if you can get enough haste on your gear or with gemming (around 250-300 rating seemst to be the break point), expertise becomes irrelevant. With enough haste, those dodges won't cripple your rotation. That is, as long as hit remains capped. Sims actually rate hit much higher prior to the hit cap, but I put in a semi-random number just to ensure I am capped when all is said and done. If you DON'T have a lot of haste, then you should try to keep expertise up a bit.
As you might have guessed, any time new content is released, I add to this spreadsheet to help me prioritize gear selections. In any case, for those of you who are interested, here's the BIS list I came up with. Arguments can be made for the gloves over the legs for non-set piece, but I think the legs' greater haste wins out. You'll also notice I find Halion's leather bracers to be the best, although the plate ones are quite nice, too, but the itemization is better with the leather piece.
Good luck to all in gearing up your Death Knights!