I see little mention of Seize the Moment teamwork feat. Sure, it's pretty endgame by P:K standards, particularly for 3/4 BAB classes. But it would seem having a couple of melees with wide critical range (like a scimitar or rapier), Combat Reflexes and good AB would chop any enemy to pieces with tons of free attacks.
Well, Greater Trip also trades 1 attack for 1 AoO + 1 for everyone around the enemy when he gets up (if successful).
The Critical feats look pretty sexy as well (Staggering Critical, Exhausting Critical, Blinding Critical - okay, the latter two are even more end-game).
Or does noone really care about melee at this stage of the game?
With amount of enemies throw at you, melees just need to chop enemies hard CCed/half dead from mages and any melee can do it.
Scouts are immune to Blindness.
You should test this and check DCs. The DC is 10 + your BAB I believe, if enemies on high difficulties have higher saves they will never fail it. If you are 3/4 BAB, it will be around DC 23 endgame? Enemies rarely have less than +20 so...
I recently fought draining baddie in a crypt with Disruption weapon on paladin. Disruption (death on failure for undead) is ~15 DC, his Will was +15.