Not really an AIBU but a WWYD
If you were a single Mum and had a 11 yo DS and a 16 yo DD, who didn’t want to share together on holiday, but you could only afford a two bed place, which child would you share a twin room with, and which would you give the double room?
Neither room will be horrible, I don’t mind sharing with either of them. 11 yo has ADHD.
It’s only three nights in the UK but getting three rooms isn’t an option.
Feels like the wrong message to give the big room to the younger, male child, but equally if it was a dad with a 16 yo DS and 11 yo DD it would be a no brained to give the girl their own room!
Edit - I’d be happy to give either one the run of the twin room during the day and would only sleep there