I've become an enthusiastic convert to Kipling bags for holidays. My favourite is a black and white stripe number from the Vintage collection. It's 38cm long 23cm high with a 13cm wide base but looks way smaller because it's unstructured.
It's a veritable Tardis - easily swallows my netbook, mobile, kindle, large purse/wallet, small umbrella, make-up bag, etc, without looking over stuffed and has a zipped back pocket which is useful for travel documents.
Kipling bags weigh virtually nothing and when I go back to my leather bags I'm always taken aback by how heavy they are after I've transferred my life the contents.
They're also washable, have waterproof linings, pockets for pens, phones, and whatnots, and some have a key holder attached to the inside which is useful if there's only one key to lose a property.
Check out the Kipling site and then compare prices on eBay and also QVC who stock a good selection and deliver quickly.
Btw, the Kipling monkeys are detachable, can be used as key rings, and kids love 'em!