Seat room question

[Ms Tree]

Booking travel on AA.  One flt is on a 737 and the other a A319.  Looking at the seat map the out bound is sparse.  Wife wants to book the extra leg room seats.  It says there are up 6" extra room.  The "up to" is what gets my attention.  In row 7, 8 and 9 on the 737 and 8, 9, 10 on the A319 is there more room or are they just closer to the front of the cabin.  
 
I'll pay a few buck for leg room but not to be up front.  I looked on the map and a few other places and cannot find any info.
 
Thanks

 

[xUT]

http://www.seatguru.com/airlines/American_Airlines/fleetinfo.php

 

[jimntx]

Wish those charts would use the same terminology as the airline.  For instance, every one of those a/c in the chart have MCE--Main Cabin Extra--but the 757 is the only a/c that uses the actual term in the chart.  To answer the original question, yes the MCE seats do have extra legroom.  If you get the "right" row there will be a table top device over the middle seat also; so, no chance of someone in middle seat.