OMG Claire I was reading your requirements and wondering if my partner met all of them never mind my bag.
Suz, I have been looking on e-bay at the brandless bags (a few YLFers have bought them and given really good reviews) and thought this one might be close to what you are looking for in a bag. I am considering the medium yellow to add a bit of yellow but not too bright.
http://www.ebay.ca/itm/2208030.....1423.l2649
I am not suggesting you e-bay a bag but that the style may be close to what you need. It has some structure but doesn't look stiff, has some detail but not too much and the shoulder strap is long enough for the shoulder with a coat but not really long. It is also a nice size.
I liked the original bag but agree about the braided strap.