first and foremost, as unholy i have never ever had aoe aggro problems, with or without wandering plague.
WP does bring a good amount of DPS for the points invested, it does help, and if you throw on DPS gear it scales very nicely due to increased crit on dps stuff.
that said.
there are a few general ways to go,
of course you always go 5/5/5, but you can get lichborne or get improved icy touch (i personally recommend if there isnt a prot war in the group)
after that, its really up to you. personally i think AMzone is a waste of 6 talent points. the only couple fights i feel its worth it on, it has too long of a cooldown to make a world saving difference, and it wont last long enough for my tastes.
After that, the only other comment i would make is 2h weapon spec only works on your physical attacks, bladed armor works on everything. you should probably get bladed armor.
Also, side note, i highly recommend getting dirge. RP helps a lot, especially when you are going to be rune strike spamming.
I also argue for are virulence, as it closes the hit rating caps between melee and spell and unholy does have a moderate amount of spell hit related things (obviously not as much as frost).
On a pale horse pwns, i'm dpsing as frost right now since we didnt have a shaman over the weekend and it just sucks not having it. I think its worth getting even though it doesnt really help your dps or tanking much, simply because it does close the gap between the upper and lower half of the talent tree, and because it is made of win.
I OT with this build.
http://talent.mmo-champion.com/?deathknight=0055000000000000000000000003050000000000000000000000000235232300020105203100203133151&glyph=000000000000
its nice because it has a good amount of damage there when you want it.
It is lacking lichborne which is arguably one of the better/best talents for boss tanking, but i primarily off tank and assist in dps as my guild is hurting for more damage right now.
Sorry this is an amalgam of thoughts at the moment, i'll clean the post up later. DK tanking is really just DPSing with a couple tank talents and some gear, so just try to focus on what would be best for dps while remembering you will be moving a lot. From there on out its all skill.