Hi Mark,
Welcome to the Disney Parks Moms Panel! I love that you are making advanced dining reservations!
As you have discovered,
Be Our Guest restaurant is a wildly popular restaurant that gets booked quickly, especially for dinner. If you are flexible, you could try making a reservation for breakfast or lunch. The castle experience is still quite lovely although the Beast does not make an appearance. Otherwise, my advice is to keep trying. Cancellations do happen. In the past, when I have helped friends secure reservations, I just picked a night where I continuously checked online for availability. In my experience, when cancellations do happen, they are for later dinner times (i.e. after 8:30 p.m.). I have also seen families on two different occasions walk up to the restaurant and get a same day reservation. Although this is unlikely, I have witnessed it!
My family now prefers to do pre-park opening breakfast reservations at Be Our Guest. We love to enter the park before most other guests and take a few photos on our way to the restaurant. If you try this, be sure that there are no early morning
Extra Magic Hours. When we have reserved an 8:00 a.m. breakfast reservation, we have been able to enter the park by 7:45 a.m. On our last visit, we dined at Be Our Guest and were done by 8:45 a.m. When we left the restaurant, we saw that cast members were letting guests ride Seven Dwarfs Mine Train. So we jumped on and were able to ride before the crowds descended!
Mark, if you have your heart set on dinner at Be Our Guest, keep checking for cancellations. They do happen, but it will take some patience! And, as always, remember character experiences are subject to change.
Magic, memories and Minnie Mouse hugs,
Donyell