You'll enjoy the commute that direction in the morning as the winds will usually create a tailwind. The route is heavily used by ebikes during commute times, I sometimes see more ebikes than analog bikes.
I usually don't recommend any particular brand, but you'll want to consider your bike setup as a complete system. What I didn't take into account was how I was going to carry all of my work stuff and spares. Also, giving some consideration into overall comfort, all-weather capability, and battery range. A strong headwind on this route will zap a battery if you ride in the highest level of assist. A 500wh battery is reasonably adequate, I wouldn't recommend anything less than that for 18 miles if you charge at work.
If you are debating a light mountain bike, like a hard tail vs a city bike, it'll boil down into frame geometry and practicality. The mountain bike setup could be good dual use bike if you want to ride it on the weekends. The city bike or commuter bike will likely be outfitted for more of an upright riding style, have fenders, and lower rolling resistance tires.
I think out of all the people that I've met riding ebikes for commuting, about 20% are on DIY setups, 40% on mid-drives (Bosch, Brose, Yamaha), and 40% on rear hub motor bikes. In my unofficial ebike group, most of us each commute 3000-5000k miles per year, with a more people transitioning to hub-drives from mid-drives. I think we had the transition away from mid-drives due to accelerated drive-train wear on cassettes and chains.
For sales and demos, you're in luck because the region has a good number of ebike specific stores, there's Ebike Annex in Palo Alto, Pedego (Palo Alto), Motostrano (Redwood City), and New Wheel (San Francisco). I'm sure I'm missing a few but those are the big ones that come to mind. Good luck with you search!
