Post meta select input, if statement

I can’t test this but it looks like something like what you have should work:

if ('option1' == get_post_meta($post->ID, 'item_one', true)) { 
  //do something 
} elseif ('option2' == get_post_meta($post->ID, 'item_one', true)) {
  //do something else
} else { 
  //do something else
} 

You didn’t need all those opening and closing tags, and some of them would have caused odd results.