I posted some in another thread of yours but here's a little more...
I recently flew IAH-BKK on a NW ticket in coach...CO metal to LAX, NW metal to NRT and then BKK. If you're flying coach, I would seriously consider taking NW across the Pacific rather than CO. I found the NW seats to be far more comfortable, and I was able to easily procure bulkhead seating on all four legs, with almost unlimited legroom. It really made it easy to sleep and easily made up for the lack of IFE. The elite upgrade from LAX-IAH was also nice (on a 777).
I paid 705 incl taxes for the whole trip. Just browsing Travelocity, the lowest fare on either CO or NW is currently over 900, though it is upgradable. I would imagine the fare will go down again before the year ends if you're still interested in flying coach for cheaper.
Row 21 on the 742 is excellent (I had a window on LAX-NRT and preferred it over the aisle. Do NOT get row 21 on the 744. Go for one of the exit rows or possibly a bulkhead at another row. I had 21J and although I had unlimited legroom, I was right next to the Galley and right in front of the lav. Very unpleasant (though I did manage to get about 4 hours of sleep on the flight). 35 B,C,H, and J would be ideal.
As already indicated, domestic legs will be eligible for EUA.
For the amount of miles you get, its a great run, though I did it more for the actual trip to Bangkok than the miles.