As for save or dies, kill them. Get rid of them. The 4e mechanic is drastically better and introduces not just more fun but more dread, and I've adopted it to my non-4e games. D&D has always grappled with horror and how to implement it, and here's a big major awesome tip to DMs (Seriously you'll thank me for this, it's the best advice for horror you'll see about the game) - horror is not "Hah hah you failed your save, you died." That's not scary. It's annoying. It's irritating. It's stupid. It's frustrating. It's not scary.
Scary is "You're body is slowly solidifying into stone; at this rate, you won't be going much longer." And then in the next round, "You feel your arms and legs creak and slow, and cracks begin to fade away on your now grey skin as it spreads even farther." And then in the next round, "You kill the medusa, and the march of petrification across your body begins to reverse. You've survived."
That's awesome, dramatic, and scary as hell. It's the difference between a slow building tense scariness, and some guy in a closet jumping out and yelling "Boogity boogity boo!" In the first example, when are you going to be scared? There's no moment of fear. Just "Welp, you're gone." In the second example, there's lots of time to be afraid. A slow death is drastically scarier then a sudden one.