We flew on board an Airbus A350-900 from San Francisco to HongKong on the way to Bali for our Thanksgiving break.
Booking
We had quite a few Chase Rewards points so wanted to use those to go to Bali. We considered transferring points to a number of airline partners or just buying the ticket through Chase. There was availability on United/Star-Alliance and that would have used up 85k points for economy to Bale (airport code DPS). Since we had Chase Reserve, buying a $900 ticket would cost $667 odd so we ended up buying through them. We chose Cathay since it was the quickest route on a reputable airline (one stop both ways with relatively short layovers in Hong Kong). Booking was smooth but since we got the cheapest fare, we weren't able to reserve our seats until checkin. That was quite annoying as we ended up not getting seats together even though I checked in exactly 48 hours before the flight (when checkin opens). We got seats across the aisle from each other.
SFO experience
Since we were leaving on the Friday night before Thanksgiving, we expected a mad rush at the airport and security. We got to the airport early and there was only one person ahead of us in line for checkin. Checkin was smooth but the agent told us that the flight was full and she couldn't get us seats together, to try our luck by convincing a passenger to move. Pity. We had Global Entry to got TSA precheck with helped us get through security a bit quicker (and easier since we don't have to take laptops out etc). We had plenty of time so spent some time at the KLM-Airfrance lounge (we had Priority Pass due to being Citi Prestige card holders) before heading to the gate. Despite that, we got to the gate before the plane arrived.
Since we had the last row, we were in the first group of economy passengers to board.
Seat
This (newish) plane has a 3+3+3 arrangement in economy. We got aisle seats across from each other. We happened to be seated next to two couples so no dice in persuading someone to move so that we could be literally next to each other. This is a modernized seat with a large screen (11.1") IFE, the place to put a tablet or iPad and USB ports. The seat bottom moves forward as the seat back reclines to minimize impact to the passenger seated behind you. This wasn't an issue for me as I seated in the last row and there was no one behind me. Yet there was enough space behind me to recline. However, in this plane, these seats didn't have any overheard space.
We had to place our bags in the rows ahead of us, not the best.
IFE
The IFE was more or less state of the art with a tail and a forward camera. Good navigation. But, of course, no prayer times or qibla direction. The camera was quite useful though.
Food
Cathay offers a vegetarian choice for the main meal only, not for breakfast so I recommend ordering a special meal for muslim consumers.
Restrooms
Even though this is a new plane, I was disappointed in the restroom. The taps were not autosensing (you had to tap the top to switch on). The sink was decent sized though. But the most disappointing aspect was the poor condition of restroom a few hours into the flight. The sink was clogged and the trash bin was full. The floor was dirty. The sink was clogged in both the restrooms I happened to visit so it was a perennial problem. And the staff didn't seem interested in cleaning the restrooms (some other airlines absolutely clean during the flight). And I've flown a350s in Singapore and Thai and have not seen this issue so it's not the plane.
They also didn't have cologne, toothbrushes or shaving kits available. Singapore has those in economy (as well as mouthwash).
Prayer space
I was going to pray at the front of the rear most compartment but when I asked the steward, he was very kind and moved the cart and trash bags from in front of the rear galley to allow me to pray there, that was very sweet and convenient. Although the a350 is wider than a 787, it is not as wide as a 777 nor, of course, a a380 so I still prefer the latter two in terms of space.