I have only done the regular dining, not the picnic. We got a good spot and it was lovely to have a lot of room (most of the other sections didn't seem to have that luxury). You also know WHERE you will be, whereas with a picnic you could feasibly maybe end up in a wet zone or somewhere that isn't a prime viewing location.
But that said, I think overall you'd be more likely to get a good spot with a picnic package and getting in line BEFORE the time on your FP, than you would to get a good spot if you got the dining package and showed up near the end of the time on your FP. Your goal is to get as close to the railing (or a rope walkway or wall) as possible, so there are no heads in front of you.
If you'll be crushed if you don't get a good spot then the dining package might be a better idea. Also, currently the dining package is in an area that isn't very full at all, so at least on Friday 6/11, kids were able to run around in the area a bit.
Conversely, if you don't mind packing ponchos just in case and are willing to get to your designated section before the time on the FP, then you might want to go for the picnic. If you eat at Ariel's or even WCT, you will get more food than if you got the picnic meal, so you aren't getting equivalent meals for a lower price. Wwe ate on the cheap (I think I just had a bag of Fritos and some grapes) on Friday and then at WCT for the WoC dining, and I had room for some popcorn after! If you have the picnic for a "meal," you might need a snack later so that might negate a bit of the savings.
But overall, I think the picnic is probably a better deal. I'm not at all sorry we did our dining package, and it does feel a bit more "exclusive," but there's a pretty significant price difference. (We had 3 adults all on our own, so it wasn't a $100+ price difference; it came out to about a $25 difference for each of us, so that was spread across three incomes.

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