I was glad to see this thread--I feel like I struggle with this all the time!
I need to carry a laptop (ugh), notebook/papers(trying to ditch these and go all digital) water bottle, snacks/sometimes lunch, cosmetic case, wallet, and for now since I'm nursing my baby, a small cooler for expressed milk and all the bottles and junk that needs to go with that. I take a bus then it's a short walk to the office.
Just when I think I find a system that works (one big bag, two small bags, or purse + laptop bag, etc.) I get sick of it and need to try something else!
Currently I've been carrying an MZWallace which is big enough for my laptop, notebook, cosmetic bag, wallet. Then an unstructured re-usable fabric bag for everything else. Love the MZWallace due to the number of pockets and the organization, and I switched to this from any of my Coach bags because the nylon is durable, and in the winter months can take a better beating than my sophia, lindsey, chelsea or caroline! But generally in nicer weather I carry a larger Coach bag that will fit my laptop too.
I just got the large saffiano city tote and it fits everything I listed all in one... but it's pretty huge. I do love it because it's such a gorgeous looking bag AND it has a separate compartment which fits my laptop and other great pockets inside! I'm re-thinking this bag though, because it's wider than me when on my lap, so this could be a pain on the bus. Also I'm not going to carry the cooler/bottles for longer than another couple months, so beyond that I think the large saffiano will be overkill.
Interested in hearing if others have any good recommendations for the "extra tote" that carries lunch, shoes, etc! The unstructured one is driving me bananas and I feel it doesn't look all that great.