Google Sites now supports custom layouts for header height, sidebar width, page width and text box width. You can also completely remove a site's header and/or sidebar.
To embed a document, spreadsheet or presentation from Google Docs, you can now browse your document list from within Google Sites rather than finding the file to insert in a separate browser window and pasting the link into Google Sites.
Standard, Premier, Education and Team Editions
How to access what's new:
To change your site's page layout, click 'Settings', then 'Appearance', then 'Site Elements'. Click the 'Change site layout' button to make your changes.
To embed a document, spreadsheet or presentation into a page, click the 'Edit page' button, click 'Insert', choose the type of file to embed and then choose the right file from your Google Docs list.
For more information: