I like 13 inches on the long side for all my portfolio prints
Since I work using 8x10 and 4x5 these days I have two sizes of exhibition prints.
18 inches long side
28 inches long side
I have been producing in this size and all my frames are suited to these sizes.
I am now working on a series of prints that will be 48 inches on the long side, I am photographing very simple small objects in this wonderful light tent using an old Century Camera with a beautiful 480mm lens.
I am about to turn my Durst 2000 on its side to get this magnification , I already have the sinks and trays . Vertically enlarging is too difficult
with this large size as it means a lot of bending down to the floor and putting the paper in place.
Horizontal printing is much more eloquent and it avoids the embarrassing plumbers backside if I have assistants in the room watching me .
I thing the contradiction of small object to very large final image is quite beautiful to behold.
For my medium format negatives and 35mm negatives I am planning to make pt pd or Colour gum over pd.
these will be in the following sizes
8 inches on the long side
13 inches on the long side
and if I get really ambitious 22inches on the long side.