Digital BW, The Print

Several months ago (6-8) there was a thread related to frame size 
and mat cutting for exhibiting prints. I tried to search the 
archives but was not successful.  the issues are - I have 12 prints 
of various sizes(5x7-11x15) that need to be matted and framed. I 
understand to use 16x20 frame size for all sizes( is that correct?) 
for consistancy, and to cut the mat 1" higher from the bottom? any 
help would be appreciated.
  
PS. Paul Roark, I love the UT-2 ink sets and the curves you have 
worked so hard on. Thanks.
Patrick