I bit the bullet and got the Lo& Son's Seville laptop tote -- the 13 inch one (my laptop is 13 inch). It is not too overwhelming to my 5'0 frame, which was my key requirement.
What I like about it:
1. It comes with a leather shell and you can collect shells in various colors. I got it with basic Saffiano black and the leather is quite nice. I intend to get a second shell for the spring/summer (maybe white, maybe red... haven't decided yet).
2. It comes with a nylon "inner" that has a sleeve to go over your carry on bag. The nylon inner tote is super lightweight for travel, and you don't have to worry about it getting dirt on it when you put it under the seat in front of you.
3. You then tuck the leather shell into your carry on. It fits mine perfectly; I tuck my folded clothing inside an Eagle Creek Packet and then inside the leather shell, and lay that on top of shoes, toiletry kit, etc. This works if your trip is only a few days long. If you have a longer trip and need to pack more clothes, then the shell may not fit. In that event, I leave it at home and just take the nylon part. Of course the shell would also easily fit in a larger suitcase if you are checking baggage.
4. It has lots of compartments to keep you organized, yet remains compact and fairly flat. I can fit inside it: laptop; book (or iPad); charger and other cords, sunglasses, keys (it has a fob), work badge, snack, headphones, scarf, and then I use the Lo&Son's Waverly for wallet and phone and other purse stuff which can also fit inside. (I really like the Waverly as well: it's quite small and can be converted from a cross-body to a waist bag to a wristlet) You can squeeze in a water bottle as well, though it may not zip closed with that.
5. It zips closed!
What I don't like about it:
1. The straps. The leather is not that great quality compared to the shell and the straps are kind of stiff.
2. The snap that holds the strap to the shell: one of the snaps on my bag keeps coming unsnapped.
Regardless of those two issues, I really love the versatility of having "two bags in one" -- or more, if I get another shell. A vinyl tote with sleeve for comfortable travel, converting into a more professional looking leather bag once I arrive. As well as the size for me, and the fact it's not too wide at the bottom.