Attribute Annoyance

I have a store that sells perishable items and I have a dropdown box that allows the customer to select the delivery date. The dropdown is always 45 - 50 days in advance.

I enter each date individually but if it is a Saturday delivery there is $12 extra charge and if it is a Monday there is a $5 extra charge otherwise it is flat rate shipping.

When I add a week to the dropdown, I must manually update the new dates to each product individually because of the added price attribute. Is there a way to update all the products globally? As it is, it takes about four or five hours.

If it is not possible, it would be a nice feature in a future release.

When I add a week to the dropdown, I must manually update the new dates to each product individually because of the added price attribute. Is there a way to update all the products globally? As it is, it takes about four or five hours.
If these products are all in a category you can alter one and copy this to a complete category and/or copy to individual products if necessary

That is the way we do it by category. It took four hours last night with 600 products.

We are about to install a cart that will have over 600 categories and 25,000 products. We may not use Zen-Cart for this. It would take a week to update one attribute.