Would this avoid the "direct flight" mileage problem?
 

I've read and experienced that when DL/NW has a flight with a single number that if you are flying from city A to C, you only get that mileage, even if en route the flight stops in city B.

But what if I ticket (as one ticket), the flight A to B on Delta then B to C on Northwest (assuming its actually the same flight - Orbitz seems able to do this, say for example SEA-NRT-HKG )? Would I get the full mileage, or do I still only get the SEA-HKG mileage? I've done a search for threads about this, but have yet to find input on how this plays out.

I wasn't aware of this problem- I fly #101 LAX-ATL-EZE and #110 EZE-ATL-LAX a few times a year, and always get credit for each leg separately. If you have other issues with these kinds of flights, try searching married segments, or something like that...

Years ago, if you book the two segments separately (even just on Delta without using a Northwest flight number), you get mileage for each segment. But if you book it as one flight, you could get the mileage from origin to departure as if it was non-stop. I guess that still is the case today.