There may be other (and simpler) ways to do this. However, if you turn on advanced permissions, you can give individual users or groups permission to both edit and approve.

See
http://www.concrete5.org/documentation/general-topics/simple-permis...

(advanced permissions is the lower half of the page).

You can set permission by page, by area, by block or block type. And then have that permission inherited by all pages below(except where they are configured otherwise). So you could, for example, give them permission to edit and approve the main part of the page, but still require your approval for the header, navigation and sidebar.