We do the deluxe plan, so the math is a little different for us, but in general I think the DDP is a substantial savings if it matches the way you eat and a slight savings but substantial convenience if you tweak the way you eat to fit the plan. The same is true of the deluxe plan, just on a bigger scale. We wouldn't do the basic plan any more - we don't like CS every day and we're appetizer people, so the plan just doesn't make sense. The deluxe plan fits the way we eat much more closely, and is still a good deal when we skip/share desserts.
I didn't think the children's portions were too small at all. My DS is a big eater and he was fine with the quantities on the kids' meals at 7 & 8. At 9 he was doing a lot of sharing off our plates in addition to his kids' meal, but that was as much because he prefers adult foods as because the kids' meal was too small. My DD is 7 and still can't finish a kids' meal at Disney.
We're similar here - our trips are now me, DS (will be five when we go this year) and my parents (both in their 70's) --- poor DH can't go since he has to work
......for us, the deluxe plan made the most sense when I looked at the DDP and DxDP when planning our trip last year. We all like to start our meals with an appetizer, whether it's a simple salad, cheese plate or something that looks interesting....so DxDP scored ahead just on that inclusion for us.
I wouldn't say we're necessarily dessert orderers - sometimes we do, sometimes we don't....even with the DxDP we didn't always order dessert - or we didn't order one for each of us, but split one or two amongst us.....and we still saved money at the end of the trip purchasing the DxDP - I don't think there was much we ordered that we wouldn't have ordered and perhaps the reason we saved money is that we tend toward higher price meals anyway - at home or while on vacation. I look at it that when I'm eating out, I'm going to eat what I like regardless of price since we don't typically eat out frequently....I like cooking, so make most of our meals at home.....when we travel, even when we have a full kitchen, I prefer to be waited on for a change - so we're much less likely to eat meals in...even at home, our meals almost always, I'd say like 90% of the time, include a starter - salad or soup or cheese plate or something I think sounds good and want to try. So for us the DxDP aligns with our eating habits well and isn't more than we'd spend if we paid out of pocket, even if we occasionally have something in the room, or if we have a full-kitchen and grab breakfast before heading out to the parks and aren't eating breakfast out, but having a TS luch and a 2TS dinner.
What I do think is perhaps the downfall of the DxDP is the quantity of food - three full meals a day on the plan are very difficult to eat, even when you're accustomed to eating a dinner each night that includes some sort of appetitzer - I doubt many actually eat three course meals for every meal, and that's the one thing that we thought was a bit over the top! Not complaining - it was sorta nice to have dessert after lunch, something we don't normally order after lunch.....but it's A LOT to try to eat, day in, day out when you're there for a week or longer!
Trying to use the snack credits on top of all the food - really difficult....if not impossible - we just wound up buying up a bunch of stuff to take home, so it's not like the credits went unused.....but they weren't used on-site while there, for the most part!
I wish there were a way to customize the plan a bit - maybe offer a way to set up your meals and what's included and then you have what you really want! Like instead of having it be an all-or-nothing proposition - DDP that lacks appetizers and has only 1TS, 1CS and 1S per day --- OR --- DxDP that has 3 complete meals and 2S per day....maybe have a way to say, yeah, I like having table service, so in a week, 7 appetizers, 7 entrees....and well, let's say 3 desserts for the week....that way you're a bit more customized? Just a thought!