BentMikey said:+1
I have a Carradice long flap camper, it's a superb saddlebag, and I carry 5-10kg in it when using the upright.
+2
I have recently discovered the SQR system. I have a hybrid that doesn't have braze ons for a rack. I fudged the mudguards with p-clips. I already had a carradice barley saddle bag on my tourer (fitted to the saddle permanantly). Was looking at the carradice website and noticed the SQR system and treated myself to one, plus an extra seatpost block. Can now happily swap the saddle bag between bikes.
http://www.bikeplus.co.uk/ (type SQR in the search box).
It fits all carradice saddlebags, and you can get some monster saddlebags if you have a look here;
http://www.carradice.co.uk/saddlebags/index.html
The barley has about a 7 litre capacity so I can fit all my tools etc in the side pockets and my lunch and very neatly packed down blouse, trousers, clean underwear, deoderant etc. I leave shoes in the office.
I'd probably go for a camper long flap bag now - 24 litre capacity, Girlie heaven!