Um, I don't usually post much, but let me see if I got this right.
You planned and paid for the vacation. You asked for their input/preferences. You told them what the schedule was, and how much there was to do. You warned them that it would be very busy. And they behaved like this?
This has absolutely nothing to do with vacation styles (relaxed versus commando), physical abilities (scooters can and were used), or personal preferences (some people just don't get Disney). But it has everything to do with being grateful, being gracious, showing common courtesy, taking some initiative, trying something new and living up to your commitments.
You know very well your sister has issues with these things.
Don't try to cover up for her, and don't try to understand her point of view. Accept her for who she is, know that you did much more than any sister could be expected to do, and pity her tremendously in that she missed out ona chance of a lifetime -- how sad is that?
Hope your next trip (in 2 days?) goes well. Enjoy the Poly, and appreciate while you are there that some people never get to experience Disney, and some that do never get a real taste of Pixie dust, and remember how sad that really is.
Bon voyage!