I'm working on a series of children's books -- 3 are finished, 3 in 'final draft' and ideas/outlines for 3 more are done. In the process of submitting work to agents (with query letters, etc.) none of the advice books clearly state where the illustration comes in. Do I have to contact one first (one of your posts says no), or note in the letter "to be illustrated in the style of..." and list some the are close to the creative direction I want?The publisher will want to choose the illustrator. And the illustration style. Not you. You'll be the least disappointed if you don't go into the submitting process with any expectation that you'll have a say in the illustration.
I'm not saying that's ideal-- I personally try to involve my authors in the illustrator choice-- but some editors do not. And some authors know very little about what illustration style will serve their book best in the marketplace.
If you want your book to be entirely under your control, then that's what self publishing is for. If you want your book to have the benefit of a team of people who know the industry and how to sell books, that's when you submit it to publishers.
Publishers are sensitive to the difference, you know. Every one of us knows at least a couple authors who feel they should be in charge of every little thing, and who resent the interference of their editor, their designer, their marketing department... etc. And every one of us doesn't want to work with those people ever again if we can help it.