Originally Posted by YesHyM

And the terms and conditon of the LAX to DEN promotion states that "Travel on flights between Los Angeles and Denver that include a connection from another flight do not qualify for this promotion. Example, MSP-DEN-LAX itinerary does not qualify.

However, Viajero Joven might have been suggesting the following:

If you want to earn 11,238 miles for $276.40 you can register for the new route promotions on nwa.com - one is from MSP to LAX (double miles) and the one from LAX to DEN (triple miles.) Each ticket is $138.20 if you return to MSP on Monday (if you return on Sunday, the MSP-LAX fare is $158.20).

Example Itinerary:

Friday, June 4 Ticket #1
Lv MSP 7:05 a.m.
Ar LAX 8:52 a.m.
Lv LAX 11:45 a.m. Ticket #2
Ar DEN 2:51 p.m.
Sunday, June 6
Lv DEN 4:00 p.m. Ticket #2
Ar LAX 5:19 p.m.
Monday, June 7
Lv LAX 3:45 p.m. Ticket #1
Ar MSP 9:11 p.m.

Play around with the dates. Register and buy your tickets by May 31 and travel by June 30.