Assign specific template to specific pages
See here Drupal 7 Theme Hook Suggestions

For nodes You can use


  node--[type|nodeid].tpl.php
  
  base template: node.tpl.php
  
  Theme hook suggestions are made based on these factors,  listed from
  the most specific template to the least.  Drupal will use the most
  specific template it finds:
  
  node--nodeid.tpl.php
  
  node--type.tpl.php
  
  node.tpl.php


Also Drupal 6 Template Suggestions

To use same tpl for multiple pages you need to use theme_preprocess_node Like

function theme_preprocess_node(&amp;$vars, $hook) {
  $node = $vars['node'];
  if(in_array($node-&gt;nid), $myuids)
   $vars['template_file'] = 'your_template_file';
}