Hi Candace!
Personally, my strategy would be to pay for one of the two credit meals at Cinderella's Royal Table or Mickey's Backyard Barbeque so that the remainder of my meals were covered by the dining plan.
Which is more economical will vary slightly depending on if you're planning on Cinderella's Royal Table for breakfast, lunch or dinner. If you're planning on breakfast or lunch there, it will be slightly cheaper to pay for that meal out of pocket vs. Mickey's Backyard Barbeque. However, if you are planning on dinner at Cinderella's Royal Table, it will be slightly less expensive to pay for the Mickey's Backyard Barbeque dining experience.
If the Free Dining Promotion is extended to cover your vacation dates, most times you will be able to take advantage of the deal. If you see a great deal announced on the
Special Offers page, be sure to call Disney at 407-939-7675 and ask if you can apply it to your reservation. If it works out, you should be able to upgrade your dining package as well.
Hope this helps! Have a great time!