Forgive me for sidebusting here, both as a normally ubuntu user and the occasional windows 7 gamer. I've been playing with FC18-lxde in a client project for the last few days, but have been actively lurking the systemd and wayland MLs since they were wee footnotes on LWN, and frowning my little heart out at *ubuntu for keeping upstart over systemd. But hey, least it isn't the tangle of LFS sysv scripts or openrc!
My Asus netbook currently has the exact settings you speak of, under windows 7. If the machine is on AC, display off. If the machine is on battery, suspend. I find myself instinctively pulling the cord out before closing the screen when I'm about to take it somewhere. Just consider it another plus one to the idea, since I think it's Asus's fancy 'superhybridengine' power profiles that seem to invoke this behavior.
Can't complain, since they threw a free windows license in my face, might as well stick steam on it.
On the upside, FC18 ships with systemd 19*, so it'd be pretty sane to send a patch to the ML and expect to be able to build and utilize the resulting fix. (haha, systemd-44 patches? YGTBSM.)