Are there any rucksack-style changing bags which are non-ugly? I have trouble with my back when I carry anything heavier than a light handbag on one shoulder. Also hoping to use a sling for carrying as much as possible, so think two shoulder bag will be easier to negotiate with that. But are there any around that are not boring and black or just plain ugly? Otherwise I'm thinking I might as well use my boring black work laptop bag rather than shell out for something particular.