I'm on the latest kernel (Arch btw) and I still have to manually "sleep" my Dell XPS 9500. To add insult to injury, it's not even "real" S3 sleep. It's Microsoft, "we want access to your machine 24/7" S1 sleep.

To be fair, I haven't spent much time in the last year messing with any of that. I do miss the days when I could shut the lid on my old Thinkpad, it'd sleep, and I'd open it a day later to an i3lock screen, and it would have only drained a percentage point.