I saw that you'd done a bunch of stuff; that's awesome as far as I'm concerned. I was away over the weekend and then got slammed with work to do on Monday so I haven't had time to do anything on the wiki, but hopefully I will this afternoon.
One concern I have is that since the vast majority of the content here is going to be simply restating what's in the books, in one form or another, we should be careful not to tempt any legal threats on the basis of copyright infringement. I'm a little worried that full synopses of each book's plot, like the one you did for Dawn's Big Date, could be viewed as being a copy of the book's contents and could lead the Scholastic folks to try to shut us down if they come upon the site. (Even though they're not actually selling Dawn's Big Date in any form at the moment.)
As for what should be on the standard book article: I think the tagline from the book's cover would be nice, and maybe also the paragraph on the back of the book (which I'm assuming would be okay to copy since I believe it's the same description used on the Amazon site to advertise the book). Speaking of Amazon, maybe we could have a "Buy this book" link to the page there, or another bookstore site where the books are actually available new or used. Definitely there should be some plot summary, too. And trivia and goofs (this is starting to sound like an IMDB page).
One thing I've been thinking about, since before this wiki was actually created actually, was the possibility of including more subjective stuff, like a section where people could enter their reviews of the book, or could discuss stuff from the book basically in the same way they do on the LJ community. I don't know how other people feel about that. There is an easy way to add a "Comments" section to any article, if we wanted to do that, or we could set up a second article, like "Talk:Dawn's Big Date", for each book where people could post whatever. And/or we could just link to discussions about the book that have taken place on LJ, or on message boards. Or we could just try to keep it encyclopedic, although even if we decide not to put discussions on the Wiki I do like the idea of putting in links to discussions elsewhere.
Oh—we could also put in Claudia's outfits in each book (which I'd like to also compile in a list), and a section listing any pop culture references, in addition to the separate pop culture articles (so someone could go "Hey this book refers to Fiddler on the Roof I wonder if it's the only BSC book that refers to Fiddler on the Roof I will click on that Fiddler on the Roof link and oh now I see these other books that refer to Fiddler on the Roof how marvelous this wiki is").