I've done the 9+pm flight on Delta twice now. One solo for Princess and once with the family (in what they call first class) for a cruise.
Misery.
The benefit of the solo trip was that I watched The Martian, and that has been wonderful (great movie). But I got almost no sleep. I was the walking dead when I got there. Changed clothes, freshened up, hit Starbucks, waited for my cousin who took a bus shuttle out from Daytona. So so tired.
For some reason I thought the big seats in First would be nice. I didn't realize that there would be a big huge chunk of plastic in between the seats, making it impossible to snuggle with my son and help him feel better about sleeping on a plane. DH sat in front of us and chatted loudly with his seatmate well after we were all supposed to be passed out. (grr) He slept, because he sleeps wherever he chooses to. DS and I tried so hard to get to sleep...taking our Tranquil Sleep tablets, we had blankets, etc etc...but it was awful. At around 2am eastern time I woke him up fully, told him to put on a movie, and just stay awake and quiet, because he was kicking and groaning and being super obnoxious (the kid has NEVER done well with fractured sleep, and with him being 11 and tall and strong, his twilight sleep was getting dangerous for me LOL). He watched the third Chipmunks movie and was amused the whole time.
That trip was for a cruise, and when we got our stateroom that day, we took a nap. Not my fave way to start a cruise, traditionally.
Those are my experiences with the red eye. I'm not 18 anymore, that's for sure.
Now the nice thing about it is that you do get in nice and early. You can change clothes when you get there (stock your carryon with what you'll need) and try to feel human. Adults can generally "fake it til you make it" in terms of being bright and chipper. Kids, though, not always. Not all kids. I was hoping against hope my kid could do it, and he rallied once we landed, but that midnight thing was rough.
And the nice thing about the Delta (and Alaska probably codeshares?) flight is that there are no stops at all. Of course, if I'd known the sleep trouble we would have, I might have gotten one that changes, just for the change in scenery.
Best of luck making that decision!
And remember, if you're looking at the Delta flight, there's no real food served (not even in first), so plan accordingly.