Good news ... it can be done ...

Bad News ... you get to start over ...

When you want US ONLY Free Shipping *and* Regular Shipping for UPS and USPS ...

Products are Marked as Always Free Shipping YES *and* Product Weight is set ...

Edit the shipping class and add the new code in red:
/includes/classes/shipping.php

Code:
  function calculate_boxes_weight_and_tare() {
    global $total_weight, $shipping_weight, $shipping_quoted, $shipping_num_boxes;

// bof: allow 1 zone only for Always Free Shipping US ONLY
// add back in the Always Free Shipping Weight for everyone
    global $db, $order, $cart;
          $total_weight += $_SESSION['cart']->free_shipping_weight;
// bof: allow 1 zone only for Always Free Shipping US ONLY

    if (is_array($this->modules)) {
Edit the USPS shipping module:
/includes/modules/shipping/usps.php

and comment out the test for Free Shipping:
Code:
    // disable only when entire cart is free shipping
//    if (zen_get_shipping_enabled($this->code)) {
      $this->enabled = ((MODULE_SHIPPING_USPS_STATUS == 'True') ? true : false);
//    }
Edit the USPS shipping module:
/includes/modules/shipping/ups.php

and comment out the test for Free Shipping:
Code:
    // disable only when entire cart is free shipping
//    if (zen_get_shipping_enabled($this->code)) {
      $this->enabled = ((MODULE_SHIPPING_UPS_STATUS == 'True') ? true : false);
//    }
First, edit the Free Shipping Options freeoptions shipping module:
/includes/modules/shipping/freeoptions.php

and comment out the test for Free Shipping and then test if the whole order would have been Free Shipping based on the Always Free Shipping setting and if so, then turn this on, otherwise turn this off:

Code:
      // disable only when entire cart is free shipping
//      if (zen_get_shipping_enabled($this->code)) {
          $this->enabled = ((MODULE_SHIPPING_FREEOPTIONS_STATUS == 'True') ? true : false);
//      }

// bof: allow 1 zone only for Always Free Shipping when US ONLY
// Only allow Free Shipping when whole cart is Always Free Shipping
  if (!IS_ADMIN_FLAG) {
    global $cart;
    $chk_weight = round($_SESSION['cart']->show_weight(),9);
    if ($chk_weight == 0) {
      $this->enabled = true;
    } else {
      $this->enabled = false;
    }
  }
// bof: allow 1 zone only for Always Free Shipping when US ONLY

      if ( ($this->enabled == true) && ((int)MODULE_SHIPPING_FREEOPTIONS_ZONE > 0) ) {
Next, add the Zone Definition that you created for the United States to the Free Shipping Options freeoptions shipping module, so it is only available to the United States ... providing the whole cart is marked as Always Free Shipping ...

Nifty eh?