I'm writing a novel. I also have good drawing skills. I would like to add illustrations of the setting, locations, and characters. I may include 8 or 10 illustrations (the novel is approximately 200 pages long). I have never seen a novel with illustrations. I wonder if readers will feel like they are reading a children's storybook if I include them?
I don't think you need to worry about "seeming like a kid's book," I think you need to worry about making a professional submission. On two points:
- Why do you think your novel should have illustrations, when most don't? Do they add anything more to your story than similar illustrations would to other books in your genre? If not, then whatever considerations apply to illustrations in most books, probably apply to yours as well.
- While "good drawing skills" are great to have, even if a publisher is persuaded he does want to include illustrations, that by no means implies that he wants yours specifically. Illustrations will be a huge element of book design and presentation, and it's generally very important to the publisher that he keep complete control over that.
If you're self-publishing, then neither of the above apply, and I see no reason why illustrations shouldn't be a colorful addition to your work. But the same considerations the publisher might have should still be considered: you want to make sure your illustrations are really appealing and look professional enough to include in your book, and that they're inserted well into the overall design and layout. If not-so-great artwork is inserted in a careless manner, that might make the whole book seem very shoddy.
No, people won't feel like its a children's book. As other people said, it is relatively common in adult literature. But know that it is unlikely to actually happen unless you are well-established. It increases the cost of printing tremendously, since images have a much higher printing quality necessary to "look good" than words do. Typically only with "guaranteed successes" like Brandon Sanderson's The Way of Kings do publishers take the risk of including decent illustrations.
If it is not possible, an alternative is posting them in full glory on your web page as an extra, and referencing the page in the book. Invested fans will seek out that material.
I can see that, in the context of a night in an art museam, pictures of items or interest would be useful and informative. If they help and enhance the story, then use them. If not, then don't - use your artistic skills in other books.
The biggest danger is using illustrations because you can, rather than because they help. If they are a positive part of the novel, then use them - it makes it slightly unusual, but in apositive way, and not a childish way.