I have a no-name gigbag that I use for my traveling guitar(a Japanese dreadnought from a yardsale) and it has survived 10 transcontinental flights and 6 transatlantic flights--I tend to carry it on, but it has ended up as checked baggage a lot--it does have the heavier foam--I had another guitar I used to travel with, in an older, heavy duty plywood case, but it suffered considerable, and was finally completely disassembled in transit, under circumstances that have never been adequately explained.

Blue Jay, I must point out that a gigbag is a bit harder for a 3-5 year old to open than a hardshell case. Anyway, any guitar that can't withstand the damage that a child can do should be locked away in the closet.