Aeris - sad that your aunt didn't believe your father about the parental limitations. Maybe your father could get aunt to listen to the parents day to day caregivers, who could give her an accurate picture of their abilities. I think it's very hard to surrender your 'vision' of your parents when they're on that long decline down hill, and you don't see them often enough to really know how things have changed from what they used to be.
My mom is in assisted living, and has been for 3 years now. There are days when she's full of vim and vigor - BUT - she still won't know where my bathroom is, she eats incredibly small portions and expends great effort trying to give you food off her plate because she has too much - and she's exhausted when you get her back home. And that's just driving her to my house for a holiday dinner where she does nothing but sit there while people wait on her, and fill her plate, and then drive her back home again. Days where she's not full of vim and vigor, you go pick her up, you get her to one planned-on place, and cut it short because she's tired and needs and wants to go back to bed, so you do NOTHING that day except drive to her place, run an errand, take her home again, and then go home yourself.
It's worse than taking a toddler to Disneyland, because you can pretty well gauge what a toddler is going to be able to do, most of the time. You know their quiet times, their meal times, and their energy levels, and you can plan around them. With an old person in declining health, my experience is that you really can't plan a day knowing that it WILL happen. It might and it might not, and you'd best be gracious about it, because NOT being gracious isn't going to do anybody any good, and will only make the day more difficult than it has to be.