Sorry for not seeing this sooner. Been to disney twice and returning for a third trip.
FF equivalent 18mm-50mm is your sweet spot for 90% of the time. 24mm on FF isn't really wide enough but 20mm puts you OK. I shot a 7D and 12-24 Tokina and did alot of 12mm shots and never really felt like I needed wider but returned a second time with a 15-30 Tamron on 5D3 and felt like that was just right. It was just a heavy lens.
I'm going back again in Nov and now have the 16-35 F4 IS I can possibly take but not sure if I'll even go with Canon. I'd rather pick up another XT20 or XE2 for myself and just take the wifes camera bag and possibly pickup the 10-24 for my camera. Will be plenty of a kit
And yes... speedlight is very important.