Our family of 4 has MYW + Dining as well. We leave next Saturday for a 6-night/7-day stay at WDW & have the following character meals scheduled:
Arrival Night - Liberty Tree Tavern Dinner at MK
Epcot Day - Princess Storybook Dinner
1st MK Day - Crystal Palace Lunch
2nd MK Day - CRT Breakfast
Departure Day - Chef Mickey's Breakfast
We're also eating at Trail's End for Breakfast, Hollywood & Vine for FDP, Boma for Dinner, & 'Ohana for Dinner. (Note: We weren't doing the Princess Storybook Dinner since we were doing CRT - but then I heard the rumor that only Cinderella would be at CRT & then I found out that Ariel - my daughter's favorite - was now at PSB, so . . . 1 more character meal! I sure wish they had a really good boy character meal - my son would LOVE to dine w/ Peter Pan & Buzz!)
Our two children are our daughter - 5 years & our son - 3 years (almost 4). We may possibly have too many character meals scheduled

. (As my DH likes to tease me - we're going to WDW to eat at restaurants & meet characters.) I was kind of looking at the meals as opportunities to meet the characters w/o having to stand in line - standing in line in the hot sun w/ my impatient little angels is so not fun! And, since we have to eat, we might as well dine w/ the characters while our kids are still young enough to enjoy the "magic & wonder" of the characters. Plus, this is our 1st trip to WDW, &, since I don't know when we'll return . . . I went a little crazy w/ our meal-planning & trying to make this trip the most fun ever, you know!
Anyway, I would say that, for 9 days & w/ your childrens' ages, 4 (& even 5 or 6) character meals would not be too many - just try for variety - so it's not Chip & Dale at every meal.

(Why
are Chip & Dale at so many character meals?)