I am working on a big book to be self-published of many creative writing and art genres. I know that there is a benefit to illustrating a book of writing, but I might be overdoing putting a musical, prose, poetry, and more in the same book. I'm still doing this one but should I concentrate entirely on a theme or just a genre when doing books?

-- Donald "Maliger"

This might be a bit too general a question. The only answer I can give is just as general:
Maybe you should consider who your intended audience is, and figure out what they would pay money for... and make the decision based on that. Conduct market research of your target market, and see what they want. If there is nothing like it in the market this can be good from the perspective of originality, but it can also be bad since people are less likely to put money down for the excentric.
Hope that helps,
Evan

Could you maybe give a bit more information here? How does this relate to role-playing?

the publishing/self-publishing aspect of role playing games is similar to my project in that it has artwork and writen creative works and how that is marketed is indeed up to the intended audience, but that audience is the common book buyers. I plan to reach them by emphasizing variety and entertainment, will that work or will I be trying to reach too many different groups only to fail?

I'd really like to ask Ralph Mazza this.

The only books I know of this type are usually themed in some way. For example, a book on the humor of dentistry had research articles, poems, cartoons, movie stills, fiction and essays all in one book. A lot of coffee table books do things like this, by letting the artwork drive the book, but including different types of writing in between. Their themes will often be historical or geographical.

I think there are probably better places to ask this question, though.