You didn't actually indicate a downside to using xslt, and yes it would fit your use case of a static include for a shared menu, though the better way to do it is to move all of the shared pieces of your site into the template and then each page is just its content. Sort of like using a shared CSS file.

To just do the menu, if your site is xhtml, IIRC you could link to the template, use a <my-menu> in the page, and then the template just gives a rule to expand that to your menu.