While it may sound a bit excessive to need three of the same style bag, I've managed to find specific uses for each of them.
1. The Coach one is tiny--I mean, tiny--and thus perfect for brunch, coffee dates, and the like. I can pretty much only fit my iPhone, the absolute makeup necessities, my keys (and keychain i.d. thingy), and a pack of Orbit Sweet Mint gum.
2. The Target one is essentially the same size as the Coach, but I prefer it for going out, in case I drop it, lose it, spill my drink on it, etc.
3. The Vera Bradley is close to double the size of the previous two, making it perfect for extended daytime outings. It easily fits all of the above mentioned as well as my wallet, makeup bag and Kindle.