Whether the dining plan makes sense for you, you'd have to sit down with pen & paper & get an approx of how much you'll eat. There are complete menus & prices on Allears.net
Will you all have a snack every day? Do you want dessert with lunch & dinner? Do you even want a table service meal every day?
For us, we can eat well & cheaper paying oop. With the rising cost of the
DDP, and less things offered, it's not the deal it once was. I have loaded a Disney gift card with the amount the DDPS would have cost, and used that for all our dining and came away with sig. Cash balance left over.
We don't want a dessert 2x a day, so skip the lunch dessert We don't have a snack every day, usually too full. We will occas get a treat we like. At meals we are happy with ice water, we aren't pop drinkers. After dinner my daughter & I mostly share a dessert. So that alone costs less then the DDP because we aren't paying for things we don't want.
Our last time on the DDP we had 10 snack credits left & ended up our last day buying stuff we could pack, bagged candy, rice crispy mickeys etc.
Sometimes I don't feel like being tied down to a TS every day and find it's somewhat freeing not to have an ADR each day. There are some pretty good counter service places in the resorts or parks, much improved menus.