@fitheach I've only taken the Zephyr for the short leg between Salt Lake City and Oakland, but it's wonderful.
The observation carriage does face out, but slightly raked so you're not totally ignoring others - it still feels a lot more inclusive than regular commuter trains. If you need some quite time you can retire to your cabin, which gets covered from bedding to setting during the day.
The scenery was stunning. Would love to do the rest of it to Chicago at some point.