Hmm, OK.
Well, open back headphones are better for positional sound locating, but obviously leak sound more. Someone in the next room really shouldn't be bothered by any headphones, not if the doors are closed. I know I can't hear mine in the next room even if the volume is turned up really unbearably loud and the doors closed. Easily heard with the doors open though, but such volume would be unbearable for anything more than a few seconds. Normal listening volume, I can just about hear them in the next room with the doors open.
When talking about a woman though, then all things that might be considered normal can go out of the window.
Some guy posted a thread ages ago, looking for some closed headphones after his other half got fed up hearing his headphones in the next room; and that was with the doors closed. Must have been some superwoman hearing going on there, or his house had paper walls.
Best choice of open back headphones for positional sound gaming would be AKG K702. They aren't easy to drive though and need a decent headphone amp. Soundblaster Z, will work, but it's headphone output is not really enough to get the best from the headphones. They might work well enough to still be a solid choice though. Rids57 might be able to shed some light on that (assuming he sees this thread). I think he used that combination of SB Z and K702 for a time.
To be honest, I'm not really sure what other choices there are of open back headphones that are good for positional sound gaming and are easier to drive, except the Sennheiser HD5** range.
Of course though, I am assuming that you want something with good sound locating accuracy, rather than just something that is fun and has good bass. Too much bass hinders positional sound cues and the K702 are somewhat neutral, which helps them to excel in this area. Not everyone wants that though and might prefer just a fun headphones with good bass and aren't too bothered if they can locate sounds accurately.
For closed easier to drive headphones, AKG K550 MKIII and Beyerdynamic DT770 80 Ohm are good choices. Not going to match the K702 when it comes to sound placement, but they will offer some fun bass if that's more what you are after.
Sorry for the long winded post.