Here in Madison, WI, Educational Travel (a local agency) has contracted rates with NW, that are essentially 'consolidator' fares. To Europe, these save about $100 in winter and $500 in summer off published rates (and they DO allow WorldPerks miles). Even if they don't save a bundle, they often allow longer stays or other flexibility that published fares don't have.

Trouble is--they only have fares out of local markets (i.e. Madison and Chicago--though they may have others as well, I'm not too sure).