Regarding Vayne and the recent changes to crit itemization...
I've been experimenting with Vayne builds, and some of them seem rather promising. Primarily, I've been forgoing any form of critical strike items.
For the first two items in the core build, it's nothing new, 
. Blade offers her every stat she would want early game, and Rageblade when fully stacked allows her W to proc with 2 auto attacks, which considerably ups her damage output against all targets.
After these two core items, I've been diverging from the "meta" items afterwards.
, she makes good use of every stat from it, and the empowered auto attacks pair really nicely with her Q. With the CDR granted, her Q cooldown becomes 1.6 seconds, .1 second higher than the spellblade cooldown from Trinity; so it essentially adds ~150-200 damage (assuming she won't have Trinity until level 12+) to every Q she casts, which is nothing to scoff at. Trinity also gives considerable bonus attack speed, which is Vayne's bread and butter.
I have some mixed feelings on, so it's more situational than core. It makes her ult a lot more scary, but the CDR reduction from AAs seems to have no effect on her Q after doing some testing in the practice tool. However, it significantly reduces your E cooldown, allowing you control duels/fights against divers much more effectively.
again, a rather situational item, but it can prove to be incredibly obnoxious against melees and ranged alike. It offers significant survivability with +700 HP, makes kiting melees a walk in the park and anyone trying to escape from you will have a significantly harder time doing so. However it offers very little to increase your damage output.
Aside from these items I've found 
to be reliable late game options.
With the botlane meta being an absolute fiesta right now, I've been taking her top lane. It's nothing "new," Vayne top has appeared many times in the past, but paired with Hail of Blades, makes it much stronger.
Why Hail of Blades? It makes your harass much harder to deal with, essentially guaranteeing a W proc every time it's up. Additionally, for all-in fights later in the game, it helps you stack Rageblade much faster, thus reducing the need to stack it on minions or jungle camps before fighting. Furthermore, with the recent buffs to hail of blades (75% attack speed at level 1!) it feels really good.
If the enemy begins building armor or is a tank in general, I max W first instead of Q, essentially invalidating their build/champ.