My wife and I each have a carry on. In each of ours we have a change of clothes suitable for first nights dinner, valuables (you decide what's valuable), documents, swimsuit, laptop (in mine), hair dryer (in hers), cameras, medication, toiletry bag, underwear and shoes.
We divide our medications, money, credit cards, between the two of us so in the event one of us loses a bag, purse or wallet it is not a vacation breaker.
Don't have Visa or Master Cards with the same account numbers. If you lose one and you cancel it, then both cards are no longer valid. Take a second one from a different account to be safe.