This. I've been to Disney World over 25 times and I've never had poor customer service at Hollywood Studios, Epcot or Animal Kingdom. But I've had a few "you've got to be kidding me" moments in Magic Kingdom. And some of those moments were in cool, nice weather with "low" crowds. No excuses for abysmal cast members.
Magic Kingdom is my least favorite resort. I wish I could skip it but the kids have a few must do's there.
This is why I'm excited about staying at an Epcot resort again; even the MK resorts stress me out because they're always packed full of guests and visitors.
As far as extended family, I just had a family member who invited themselves along with their family and they've been driving me crazy. We were first booked at Yacht Club club level but they wanted to switch over to the Polynesian. I'm not a fan of the dark decor over there, but okay fine.
Then they weren't sure if they were coming at all

so my family and I switched over to Beach Club club level and that's where we're staying put. Fast forward the next day and this family member had the nerve to tell me they're going "seriously this time"

but they were upset that now they HAVE to stay at BC because they want their children to room close to mine. I told them they could stay anywhere they wanted, they didn't have to room next to us (in fact I believe there is vacancy on Mars) and no we were not changing hotels.
The trip hasn't even begun and I'm already sick of them. I let them know we WILL be splitting up during the trip at some points. Yeesh.
Long story short...just don't vacation with family and don't let cast members get away with being nasty.