I'd just like to put forth this information on the proposed replacements for these aircraft, as to how they match up to the L1011 and DC-10.
L1011 (-1 to -500)
Two Class seating: 246-256
Two Class Seating: 250-270
Two Class Seating: 240
Two Class Seating: 245
Two Class Seating: 330-350
Two Class Seating: 256
Two Class Seating: 335
As we can see, the B757-300 does not have the range or capacity of either, but is much lighter, good for short hops. The B777-200 and A330-300 both are much larger in capacity. The B777-200 is also much heavier, making it not a favorable replacement. The A330-300, on the other hand, is lighter, and would be good for charter operators needing the capacity.
The B767-400ER and A330-200 seem to be quite good replacements, neither is too heavy. The B767-400ER has enough range to handle almost all routes and has almost the same capacity. The A330-200, from these few figures, seems to be the ideal replacement aircraft. It has the same capacity, enough range to cover all DC-10 and L1011 routes, and is not too heavy (weight which would translate to more fuel burn and greater airport fees).
Hope this info can be of some use to you guys! I thought it would be relavant as this is currently a big topic, partly due to the fact that we do not yet know which aircraft Northwest will choose.