I do exactly that for a couple of clients - fixed fee - keep bits and bobs updated.
This client wants control over all content on the page, they have two people in the office ready to do it.
So it would be info Boxes - edit contents
Sliders - edit images and links
all other text areas - editable via widgets or text boxes
Callout - editable text and link
Any item with a link needs to be accessible with support for alt etc
Essentially, everything that involves content management
The only thing they don't want to edit is the style of the page. That said, if someone wanted to add a couple of text boxes or a callout - then thats what a good CMS should be capable of. Having written PHP pages that automated some of this is the past I can see the huge advantage of drag and drop.