I think people of all ages can enjoy a character meal, it just depends on what your kids are into. Lots of folks love CP with the Pooh characters, but my kids aren't really into them anymore, even at 5 and 8. But they still like the traditional disney characters so we tend to go with Chef Mickeys or places like that (we are going to the TH breakfast this time).
My guess is that your son and probably your daughter are not into princesses, but 1900 PF has a cinderella and stepsister meal they might like. Their breakfast also tends to have a variety of characters not at other meals. Another good options might be the Lilo and Stich breakfast at Ohana since they tend to skew a bit older.
Hopefully someone with kids the age of yours can give you some more feedback.