I did quiet a lot of playtesting with Wights just last night strangely enough.
The adventurers were heading into a barrow full of wights, after being unimpressed with the ones I used in the first area, I mixed it up a little in later fights. I used three types of Wights.
1) I was unimpressed by the heal-on-hit drain effect as written. All it meant was that it took slightly longer to kill the wight if he hit you. It did nothing to make them fear the Wights.
2) The next encounter they encounter Wight 2.0, this was a tougher type of guy, his attack was a level-drain. More accurately a level-suppression. The PCs were 5th level. Once hit, they could not use any 5th level abilities, spells or feats. Get hit again, they can't use any 4th level ones, etc. By the end of it, they were fighting only able to use their basic level 1 abilities. The Cleric and Wizard learnt to fire off their high level spells ASAP before they lost the ability to use them
The advantage of this type of level-drain was that it required no real book keeping. It just suppressed abilities, it did not change to-hit or any other stats. I was nice and let the cleric still use Remove Affliction as a ritual, despite the level drain. He got the party up and going after the fight. After all, as a GM you don't want to bore people by making them use nothing but basic attacks.
3) When they reached the end guy, I decided I could play around with hit dice draining that I did not want to do too early in the game. So when this Wight Thane hit them, he caused them to lost a hit dice, then he healed up for the full amount of that hit dice. If they ran out of hit dice, then they instead take their dice value in damage and the wight is healed for that amount. Did I mention he was elite so could attack twice per turn?
This was interesting, as soon people were drained of dice, so the Dwarf Fighter was taking an additional 2d12 if he bore the brunt of the attacks, where as the wizard would only lose an additional 2d4 if he was the one getting hit. The Wight Thane has a much easier time draining the life out of a strong person than a weak one. Further more, the Thane was healing for 2d12 every turn he hit the Fighter. It got to the stage where the PCs just wanted to keep him away from the tough guys and the weeny guys started tanking him. The PCs enjoyed the discrepency from normal.