This may be a nitpick, and it also may be a herculean undertaking to do what I'm describing -- but is there any way to better structure the hierarchy in the directory?
By way of example -- I had a great experience with a children's book company recently (Bendon), and was going to go review them if they were in the directory, and recommend them if they weren't. Getting to books>children's books was easy enough, but many of the top companies listed there are not children's book wholesalers, and some not even specifically book sellers -- there are lots of general surplus companies who may incidentally carry books.
Fortunately there are only four and a half pages of results for that particular niche. But especially in larger niches, wouldn't it make sense for specialists in that niche to come first rather than the large general liquidators?