What modules are required to make a seating chart website?
Closest things I was able to find are Wysiwyg Image Map and jQuery Map Hilight modules. 

Wysiwyg Image Map is image Map editor for tinymce provided by the Wysiwyg module.

jQuery Map Hilight enables the simple addition of mouseover highlighting of hotspots to HTML image maps without requiring the editing of theme files or knowledge of javascript/jquery.

Together they should give you roughly what you need - but if I were in your situation, I would prefer to code this myself.