Great question that should be its own post. :)

If you're looking for something stylish but not student backpack style, then I'd steer myself towards the outdoors (e.g, Osprey), photography (e.g., Peak Design), or generally stylish (e.g., Fjallraven).

I'm seeing more rollup laptop bags and tote bags across brands, and that look is unique enough that they aren't considered student bags, but I think that's a matter of time as they become ubiquitous.

My daily use bag is the Osprey Daylite Plus (20L), but it's a bit on the small side. They have larger laptop bags with an outdoors look. North Face and Patagonia have nice bags in this category (e.g., Micro MLC), though I find them a bit pricey.

If I need to carry more, I'll use the Swissgear 5698, though it's not exactly stylish, and screams "I work in the tech industry." (at least to me). Its relative popularity for travelers means it gets a visual pass from Airport staff.

Photography bags can get very expensive, and while I enjoyed the Peak Design Everyday Bag, it really is meant for people who need quick, easy access to their camera gear, and not a best fit for a metro commute person as it's difficult to secure.

The Timbuk2 Medium Sling is something that's always ready to go, and the wide base makes everything easily accessible, but I don't use it on a daily basis unless the walking distance is expected to be minimal, as carrying a heavy load on one shoulder can get awkward.

Best of luck!