Music and Audiobooks in Library

Try changing the genre to "Audiobook." Then you may need to add the file to the library again in order for it to show up correctly. If this doesn't work, it might be because the Audiobook page of the library only recognizes files in the format .m4b. If some of your books are .mp3 and some .m4b, that could explain the discrepancy in where they show up.

To show up under Audiobook in source pane the files need to be in .m4b format or from Audible.

To make .m4b yourself you need to import the audiobook from CD as AAC. This will make .m4a files. Edit track info making sure genre is set to audiobook. Remove from library without deleting file. Change extension from .m4a to .m4b. Add to library again.

I generally import audiobook CDs as one file per disk naming the track after the book with a number indicating disk number (001, 002 or 1 of 5, 2 of 5)

The multiple chapter renaming issue is why I import each disk as one file. Edit tags before importing then there is nothing to change other than file extension.

How about command prompt "rename *.m4a *.m4b" ?

called 123renamer which allows you to change an unlimited number of files with the same extention to any other extention
Note that changing extensions in Windows can cause a file not to work.
Example - You can't just change .m4a to .mp3.

All my audiobooks are in mp3 format. Is renaming them to m4b out of the question.. ie, will they not work if renamed? Or do they need to be converted from mp3 to m4b?

All my mp3 books are tagged as 'audiobook' in the genre. I can 'live' with them not being in the Audiobook section of iTunes, but would rather catalog them there if possible.

In the iTunes library, I tag each audiobook file (actually, this can be done all at once by selecting all of them) with the followed checked:
- remember playback position
- skip when shuffling
- part of a gapless album

That way, if I choose to shuffle music, the audiobooks are bypassed. Also, they play gapless one after another so there is no pause between files. And finally, the place I leave off is bookmarked for when I return. Works for me!

Regarding renaming, I use a program called Mp3Tag ( http://www.mp3tag.de/en/ ) that is free.. not only can you change tag info, but also easily rename files in bulk. And you can sequence them in any manner. One of the best free tag edit and file renaming programs around.

If you wan to tleave them as they are, they will work.
They just will not show under Audiobooks.

You can convert them to AAC, then change the extension to .m4b.

To do the extension change it must be from .m4a to .m4b this will not work from .mp3 to .m4b

Converting from mp3 to aac will lower audio quality so either live with how it is now or re-import from the CDs.

Note that if they are audio books, you will probably not notice much of a difference in converting lossy to lossy.
If it's a song file, you will very likely notice a difference.