I do this route quite frequently. This is my advice from a United perspective for redeyes in first on this route.

If you get the 757, you are all set. Get a window seat and bring your headphones and sleep mask.
If you get the Max and the Next interior is your next best option.
Anything else is a toss up.

From wheel up to wheels down, it's usually ~4 hours, so you want to fully recline and go to sleep right after takeoff. You'll likely wake up when the crew prepares the cabin for final, so expect 3.5 hours of sleep. Be warned it took a while for me to be able to sleep with any consistency on redeyes. Everyone is different but for me at least, you can hit the ground running. It's pretty great in the morning but you are going to be very sleepy after lunch, so if you can schedule an hour for a nap somewhere in the afternoon, that's served me very well to power through the day. Sleep early that night.

Crew on this flight are pretty good about respecting everyone's sleep, but if you want more sleep, your other great option is doing PHX-LAX-EWR. I did this once and had the best sleep in Polaris.

Hope this helps, and best of luck.