I love my Onatah GM in Cuir. It is so comfortable over my shoulder and fits great under my arm.
For summer shopping, work, or travel I love grabbing my Cabas Mezzo. It has all the capacity I need and a zip top closure.
For winter shopping, work, or travel I stick with my Black Denim XL. It is huge and is great to just toss everything into. There is no vachetta to worry about so rain or other inclement weather isn't a bother. It has two crisscross straps to close the top but I am in and out of it so often that I tend to just leave it open.
I know it isn't sexy compared to others, but I LOVE my Bagnitolles Horizontal for a shoulder bag. I love thats its an LV monogram bag but it has simplicity, practicality, and a classic shape... I think its perfect for a busy, work/mommy lifestyle! Laptop, snacks, sippy cup, diapers, books, files, whatever(!) always fits and the two handles are good for over shoulder or crook of arm/hand carry.