I have a chicco bag
http://www.toysrus.com/product/index...ductId=3535414
despite the online reviews, I love it for when we will be out all day, it has plenty of storage, enough pockets, and is neutral enough I can use it for the next baby - whenever that happens - even if I have a girl.
I did have this one:
http://www.toysrus.com/product/index...ductId=2622056
and it is no good. I hate the flap thing, as there is no inside zipper we lost some items b/c they fell out. it's cute. (that is what I get for letting DH pick the bag - all style, no function! LOL)
we also have this one:
http://www.toysrus.com/product/index...ductId=2591372
which I rather like, it is small, has a long enough shoulder strap, only downside is no changing pad. (granted I rarely use one, mostly only if changing a poop or on a public changing table)
Granted, I am never toting a ton of bottles either - at most one - and that was mostly when DH was very tiny -weeks old - b/c it was easier to do expressed milk than a prolonged and challenging nursing session in public.
It depends on what you take. I have 4-6 diapers, wipes, changing pad, and two changes of clothes (a day outfit and pajamas), a paci, diaper trash bags, and teething tablets. Oh, and my nursing cover a flannel blanket/burpcloth, and a couple extra bibs - when I remember. This seems like a long list, but really it doesn't take up much space.
DS is 5 months old - and often we bring the bag with us, but it stays in the car unless I know I need to change him or I will need to nurse.