This is a little trick, but a useful one all the same. When you use the Publishing Site template for a site, you do not have the option in Site Settings to save the site as a template for reuse. There are probably good reasons for this due to the underlying structure of Publishing Sites, but no one has ever been able to explain it to me in any detail.
The trick is to append _layouts/savetmpl.aspx to the URL of your site. So, for example, if your site is at http://servername/site, you would use the URL http://servername/site/_layouts/savetmpl.aspx. On the Save as Template screen, you’ll probably want to check the ‘Include content’ box so that the .aspx pages in the Pages library are included.
Be careful with this, but as long as you haven’t done anything fancy in your site, it ought to work just fine. The template that you save will be available when you create a new site under the PublishingSiteTemplate tab.