Hi, Karl. If you want a mess-o bib records, the LC Books All file (to
2006) is at:
  http://www.archive.org/details/marc_records_scriblio_net

As you probably know, you'll find those in the 300 $c, in centimeters:
"23 cm."

There is also a dump of the OL data in JSON:
  http://www.archive.org/download/oldumps/jsondump.json.gz

That includes records from sources other than LC (other libraries,
Amazon).  That will have the size in "physical_dimensions". In addition
to the LC height in centimeters, there you will also find some that
look like: "11 x 9.4 x 0.7 inches." Those come generally from Amazon.