Aperture has a "private" metadata field that calculates the aspect ratio (such as 4x6 or 8x10) of a version (Lightroom = Virtual Copy). Lightroom has a metadata field called aspect ratio too, but it is binary; either landscape or portrait.
In Aperture I used the aspect ratio as a display choice and a filter to find my common photo sizes (such as 4x6, 8x10 or 11x14). Moving over to Lightroom I've tried both a custom color label (named 4x6, 8x10 and so on) as well as using the copy name field to manually fill in the photo size. I think I like the color label the best, but it's not perfect.
How to other Lightroom users handle this?