I’d recommend an odd-numbered window Delta One Suite. I’m 6’3’’ and never had an issue sleeping on the A350-900 to SYD from LAX.

I usually love a bulkhead because of the larger footwell, but I’ve found odd numbered seats better for sleeping on the A350. The seat itself is closer to the window. This gives you a bit of a space to bend your knees between the footwell of the passenger behind you and the door. I’d personally recommend 3A/D, 5A/D, 7A/D. Window seat numbering starts at 2 on the A350-900.

It’s some of the best sleep I’ve ever had on a plane!