Hi again Laurie,
Welcome back to the Disney Parks Moms Panel and thanks for your kind words. We truly love helping guests plan their magical Walt Disney World Resort Vacations! Most of the character dining options offered outside the Theme Parks are available during breakfast and dinner hours, however I can tell you that depending on how early your family has breakfast, you may be able to schedule a late breakfast as your lunch. We tend to book the latest seating for breakfast and we are generally fine until dinner. I find that there is so much food available during our meals, we only have room for two table service meals a day.
If you are looking for a special dining experience that takes place outside of the theme parks, I would highly recommend
My Disney Girl's Perfectly Princess Tea Party at Disney's Grand Floridian Resort and Spa. This experience would not be ideal for your 21 month old, but would be just magical for your four year old. It is a splurge, however it is my all time favourite experience my daughter and I have ever had together at Walt Disney World Resort.
Also, some fun experiences are available at your Walt Disney World Resort around the pools. They do not offer characters, however, the Cast Members and activities are wonderful! I would also suggest heading to Downtown Disney or the boardwalk for the afternoon. Again, not a character experience, but enough to keep both children entertained.
I hope that helps Laurie. Please let me know if I could be of further assistance, I would be happy to answer any other questions you may have.
Stephanie