How long can a kid use it? We are thinking about getting one for DS for a trip we're going on this weekend, but aren't convinced that it'll be worth the money. We don't go on that many overnight trips with the kids to places where they won't have somewhere to sleep, so it could be a year before it gets used again. Would a 4.5 year old fit in one? Would a 4.5 year old prefer a bed anyway?