<font face="Verdana, Arial, Helvetica" size="2">no stopovers on CO/NW</font>
Had one last year in ams on the way back from mad.
From nw site using wp miles.
<font face="Verdana, Arial, Helvetica" size="2">Stopovers are permitted only in a Northwest, KLM, Alitalia or Continental hub, or at an international gateway city that is indicated on your flight itinerary. However, free stopovers are not permitted for travel within Asia Pacific/Micronesia, or within/between the 48 contiguous United States, Alaska, Canada, Central America, Mexico, the Caribbean and Puerto Rico.</font>
http://www.nwa.com/asia/en/freqfly/travel/index.shtml