I use the Skip Hop Duo Deluxe Double Diaper Bag - Uptown Stripe . (Comes in all kinds of other colors too) You can check it out at
http://www.diapers.com/Product/ProductDetail.aspx?product...
Its a bit pricey but after buy 3 different cheapo bags that I didn't like, I bit bullet and got this one---should have done that first! Its great for multiple kids (I have 3). It has a long should strap as well as end straps to hook onto a stroller. 3 front shallow pockets and 2 deep back pockets. A zipper inside as well as mesh pockets inside. It also has two end mesh pockets.
I am not the most organized person so this is great for me b/c I can have snack in one pocket, wipes/hand sanitizer etc in another, plus I always know where my keys & wallet are without having to dig through the entire bag.
The only draw back is that it doesn't have a solid base so it tends to tip...I resolved this by cutting a piece of cardboard to fit the bottom, covered it with fabric and it doesnt tip anymore.
Again its a bit pricey but like I said---bought 3 bags in the course of 1 year, bought this one 3 years ago and have looked back since.
Hope this helps.