For me (in addition to some of those listed above):
Torque converter should be replaced. Maybe pay any extra for an upgraded unit?
Rear main seal, close inspection of flex plate for cracks-- maybe send it out for mag testing to prove failure is eminent or in progress.
F.diff carrier bearings (but can supposedly be repaired w/o trans R&R) if output drive flange is exceedingly loose.
Turbos: ensure radial and end play are within specs, or replace as needed.

From personal experience with extended warranties doing anything preventative is a tall order. Went thru a transmission issue with Nat'l Warranty Co couple years ago for a noisy carrier bearing. They heard it-- well the second "rep" did-- but it was still denied. On a vehicle with known weak transmissions. Tried to blame it on in adequate service. Total BS.