I personally think there is nothing wrong with a 7 year old in a stroller. We just rented a double from a online service for the week for our 3/7 year old.
7 year olds get tired too! It is alot of walking for anyone, especially young ones in humidity and heat on top of a ton of people around making more heat.
As for tantrums and dirty looks from others, I could care less what others think about our oldest being in a stroller. It is not their sanity that is on the line!
As for the tantrums, I for one do not put up with them and she knows it, I only need say one sentence and it usually works...
"If you cannot behave I am more then happy to go back to the room and sit til you figure out how to act like a lady" ....
We have done it before and will continue to do it. She knows mom does what she says she is going to do. I am more then content to sit in a air conditioned room all day and do nothing til they figure out how to behave.
It comes down to personal preference as others have said. Enjoy, do it, and don't worry about how it looks to others. It is YOUR vacation and YOUR sanity at stake not theirs.
Have a wonderful time!