For us having it both ways is best.
we use .htm/.html extensions so our sites all appear static, but use the X-type modifier in the .htaccess file to cause htm to be parsed as php.
the .htaccess file in the root of an apache server domain is normally invisible but can be seen easily if you set the filters in your ftp client, just google it and you'll find out how.
we just place the following inside that file:

<Files *.htm>
ForceType application/x-httpd-php
</Files>
<Files *.html>
ForceType application/x-httpd-php
</Files>

for our windows servers, we still name everything .asp even if it is static.

these things will give you the ability to post your site as static, leaving the option to create dynamic pages later, perhaps when you are ready -
WITHOUT HAVING TO CHANGE YOUR FILE NAMES ON PAGES YOU HAVE WORKED HARD TO PROMOTE.

always back up the .htaccess before operating on it!
since apache checks it before doing anything, any error at all will stop the server and a backup saves the day as you learn.

cheers!