I'll edit this post and let people know how the fit is. I like that the leather sides extend down past the bottom. My SO will have the book in a large purse and this should provide some protection when she sets it down on the floor. I also like that the top looks like it can be folded back; when this is used inside a handbag the SB can just be slid in and out and when additional protection is wanted (like carrying this stand-alone) the top can be flipped into place.
Just a followup, I have had a few days to play with that tan synthetic leather sleeve in my post above. It's great! Honestly, better than I expected. The quality is great for the price and it is just wide enough to fit the SB with pen attached. Height is just enough to close the cover as well. All in all, I'm really pleased; the fit is shockingly good given that it was not targeted at the SB specifically.
My wife and I are nomads and travel a lot on planes, trains and automobiles. For years I've found the best combination to be a nicely padded sleeve and a good, (also) padded technology backpack. My wife used an Amazon Basics sleeve like the one pictured above but we both thought the padding was a little skimpy. Now we both use the Case Logic Sleeve with Pocket for 13-Inch Macbook Pro - Black (TS-113). Nicely padded, inexpensive, fits the Surface Book with a little room to spare and with a pocket that will hold my iPad and Kindle.
This is not durable enough or padded enough for a heavy traveler. I have my Surface Pro for that task anyway. But I believe it will be great for general protection. And yes, the gawdy bright red piping really is that bright.
Well... I picked up the Kuzy MacBook Pro 13" PU Leather sleeve from Amazon. At first glance it's a great deal, especially at only $26 US. It looks nice, and fits the Surface Book perfectly. Is it some sort of high protection sleeve that will save your $3k investment from utter destruction if you drop it from 6 feet up? Not exactly... But it does provide some basic protection for when it's sitting in your bag and it looks sharp. If you slide it right, there's even room for the pen and it's got a little slot in the back to throw some papers and stuff in if need be. I'm pretty happy with it so far... Added bonus is that it goes with my Fossil Vertical Messenger about as well as could be expected!
Ordered my Waterfield sleeve early on. I am a regular customer and have probably a dozen different cases and accessory zippered bags from them. Got my Surface Book sleeve on Friday. I purchased the one without a flap but it does have a small elastic band to keep it in place. My Book fits snugly and the sleeve does not add a lot of bulk to the laptop which makes it easy to fit in a briefcase, etc. On the back is a tight mesh net which could hold the power supply. There is also a slot for the pen.
I have to add that all of the Waterfield bags are made by hand in San Francisco to the highest standards. They aren't cheap but I don't mind paying a little for quality.
I just picked one of these up also. Nice padding, snug fit bot not enough you have to scratch it with the zipper to get in. Pen can stay attached, but I prefer to remove it, as if it comes off in the pouch, it could really scratch things out.
Belkin 14-inch sleeve from amazon just 8-9 GBP and it has a separate small zip compartment on the top for my charger/wireless adapter/usb stick/pen.. Also very nice interior and good build quality. Fits like a charm and has a cute little discrete handle for carrying on its own.