1. Carry on. Assuming airlines will never lose bags is setting yourself up for disappointment. I rarely check, but when I do it is a calculus of 'what do I need to go a few days if they lose the other one'

2. DO NOT waste your time trying to find the lost luggage (aka grappling with the airline about this). Figure out a plan for getting your wife some clothes, execute the plan and move on. Assume it is gone forever; figure out what she needs to buy; buy it. And dont obsess over the $$. AA/BA should reimburse you, but they will be stingy <redacted> about it if you ASK them now. Dont nickel and dime, dont listen to them when they say 'check in tomorrow'... only to waste hours on hold to be disappointing. Especially if you are here on vacation...if it shows up, fine, if not just enjoy the vacation.