Nice analysis. Just a couple additional points of clarification:

I believe that NW only has power on its 744s and 330s in WBC and on the 330 in coach. Those are only used for international flights.

I don't think NW offers its Plats SWUs automatically (at least if it does I never got mine). Last year they did a promo where plats could earn SWUs, but they were almost impossible to obtain. In the beginning of your analysis you noted that NW, DL, and AA offer SWUs available at the time of booking (point 5) but later note that NW doesn't offer SWUs (point three under the mock booking...if they did, the total price would drop dramatically)...a bit confusing.

Again, a great overall analysis. You bring up some interesting points. This would be really nice if you could try to incorporate the premium product information (e.g. seat width, pitch, etc) for both domestic F, and international BF/B/F. It may give us a better idea if we are getting what we pay for