<p:selectOneMenu value="#{navigationBean.location}">
    <p:ajax listener="#{navigationBean.navigate}"/>
    <f:selectItems value="#{locationBean.locations}"/>
</p:selectOneMenu>

public String navigate(AjaxBehaviorEvent event)
{
    return (location != null) ? "pretty:view" : null;
}

<url-mapping id="view">
    <pattern value="/#{ location : navigationBean.location }/#{ /\d{4}/ year : navigationBean.year }/"/>
    <view-id value="/view.xhtml"/>
</url-mapping>

public void navigate() {
    FacesContext context = FacesContext.getCurrentInstance();
    context.getApplication().getNavigationHandler()
        .handleNavigation(context, null, (location != null) ? "pretty:view" : null);
}