If I recall correctly, I transferred MRs to Singapore Airlines - wasn't the best deal ~70k miles each, but I had a very narrow travel window and had to grab what was available, esp with it being so close to Christmas. We flew on the A350 ULR that only has Business and Premium Economy Cabins - 18.5 hour flight. I was dreading the flight, but wasn't too bad - it definitely helped that I snagged the exit row so had tons of legroom. Otherwise, in terms of seat and service, it was an OK Premium Econ experience, but the inflight entertainment system was very good. We departed Newark at 9.30am Sunday and arrived Singapore just after 5pm Monday. I napped about 2 hours on the plane. This worked out really well as it was not long to stay up after we arrived then went to bed about 11pm and got a good nights sleep. Did not really experience any jetlag.
In Singapore, we did the main tourist things - Chinatown/Little India/Sentosa/Gardens by the Bay. We really enjoyed the Christmas theming and the light shows - and the Christmas Wonderland was fun, if a little chintzy. Just loved how easy it was to get around and the vast number of places to eat and foods to try.
As I said, our Phuket stop was on a cruise - so can't give much of an opinion. We docked at Patong, which seemed a bit of a Party Central type place that I might have enjoyed 30 years ago. I probably wouldn't choose to stay there now, but I am led to believe there are much nicer and quieter places to stay on Phuket. Our trip was to Phang Nga Bay which has phenomenal scenery and we really enjoyed the excursion and boat ride.