Seating Issue
 

I have CO ticketed itinerary for 4 on SEA-MSP-DTW (NWA) and seats haven't been assigned. All that are available on the SEA-MSP part are the coach choice etc (20+ open). Is it possible that the flight is oversold. I understand that there would be passengers without assigned seats untill boarding.

Hard to say, based off seat maps....searching via availability on some of the ITN systems can give you more numbers of seat availbe for purchase though not always accurate....I do'nt have the link to the sites I use right now...but a quick search should find it....

Also try nwa.com "view my reservations" for seat assignments. You likely will be able to get assignments when you do online checkin too....as elites get moved forward to first class and sometimes very nice seats open up