What do you actually want from this thread?
Both of my children when aged 11 would have been bored by this holiday itinerary.
But equally, you don’t sound like you actually care, or that you want advice one way or another.
In my head it’s twofold. I haven’t had a child free holiday in almost two decades. I would secretly be quite excited if my daughter decided she wanted a week with Granny (and her Granny was happy with that). But if it was because she didn’t enjoy holidaying with us, that would make me sad and I would want to do something we all enjoyed. In an ideal world, a week with Granny and a week as a family. But that wouldn’t happen because my kids wouldn’t stay behind willingly and miss out on holidays!
But also, she is eleven. So she doesn’t actually get a choice in this. If you tell her she’s going on holiday with you, she’s going on holiday with you. She doesn’t actually get to choose to go to Granny’s. That’s still your choice, as her mum.
Your post also reads as quite exclusionary. Thinking of it from your daughter’s POV, you go for a nice comfy nap snuggled up with your husband in the bedroom and shut the doors (quite literally) on her, leaving her alone for 2 hours. You and him as a unit, her shut out. Especially if he’s her stepdad (which is how it reads), I can see that may have also upset her. My kids even in their teens love a cuddle. I wonder if this vibe has also added to how she’s been feeling about the whole situation…