Originally Posted by
avflyer
M fares don't require a Saturday night stay. Often M fares book as B (near same price) with the ability to change day of departure without penalty. M fares can be purchased inside 50 days. M + PMU works better for some than a cheap I.
Just got internet access again
You are probably correct with "M" vs "I", etc. But what is really amazing is the $2300 paid to get the right to use the PMU or other people to use miles. At AA base members could save $1600 by buying the $700 fare and paying $700 copay.