I need a carry-on bag big enough to hold a weekend's worth of stuff. I have narrowed it down to two choices--a Prada black nylon or a white Stella McCartney. Some things which may not be obvious from the pics: The Prada can be folded and put in another suitcase as a spare bag; it fits over the shoulder, but not comfortably, especially if it is full; and it has just one big interior compartment. The Stella fits comfortably over the shoulder, and has a number of interior dividers, pockets, etc., including one big enough for a laptop; plus there are a coin purse and two separate cosmetic bags. Any opinions on which I should keep?