I want to re-visit the subject on how to select the publishing companies you submit your work to because this was rather tricky to address as this choice is so individual and particular to YOUR work.
I don’t think it’s entirely fair to leave this all-important decision to the hungry, idealistic, aspiring author/illustrator. All publishers are trying to publish a Caldecott winner and who within the publishing house has the authority to decide is highly variable. Publishing houses have such different editorial hierarchies; we have heard assistant editors speak about how many levels of their company they themselves must push a book through to get to a deal. Then there are those editors where the buck actually stops with them. Know the hierarchy before you submit; SCBWI membership gives you an inside scoop on this.
Publishing companies are inundated with submissions, many of which are from those who do NOT do any homework into the company, submit sloppy work, or unsolicited work when that house only accepts solicited work. These are among the many reasons why submission guidelines have become so voluminous and strict. And as a result, we who are meticulous have to wait in that very same cue to be reviewed.
To begin, target maybe 5 publishing companies that publish the books you personally like. Chances are, the artistic or writing style you gravitate to may already be in line with the types of books on a publisher’s book list. Go directly to their submission guidelines on their official website, and look for 2 main things: whether they accept un-agented (called unsolicited, unless you have an agent) manuscripts; and if they will accept a multi-submission whereby you can submit to other publishers while waiting for them to review your work, or if they want an exclusive submission, where that house reserves the right to look at your work while no other house is looking at your work.
SCBWI conferences will put you in a room with these editors whom you can then approach (beware that hundreds of others will have the same idea as you). Try an agent to get your book in front of those companies that do not accept unsolicited manuscripts. But frankly, NOTHING replaces knowing the industry. You should know what the top 5 best selling books are, as well as which ones won Caldecott the previous year. You should be able to rattle off the movers and shakers in this industry, just as you would for any professional industry.