Originally Posted by
MSPeconomist
Often I see fare rules that require a Saturday night stay, not a seven day stay. There are worse places to spend a weekend day than Europe, and the saving on airfare can easily pay for your additional lodging and meal costs. Plus, sometimes it's nice to have a day to relax and recover from jetlag before trying to do too much\
There are fares that require one, or the other, or either/or. A Sat-Sat trip will meet 7-day min-stay fare requirements, but not Sat-night stay fare requirement (because you arrive on a Sunday). A Fri-Thu trip will meet Sat-night requirement, but not 7-day min stay. Either trip will generally be much cheaper than a Sat-Fri trip where you meet neither.
FAR-CDG May 10-16 (Fri-Thu) $1623 (Saturday night stay)
FAR-CDG May 11-18 (Sat-Sat) $1683 (7-day min stay)
FAR-CDG May 11-17 (Sat-Fri) $3733 (neither -- you get M fares)