"How is there any style to being an undead if nobody can recognize you as one?"
Er, the most popular and most fun game to play undead in, with the most style, is a (booo! hiss! d20 forum, duder! stop it) White Wolf game where the entire FOCAL POINT OF THE GAME is doing things in ways that no one will ever recognize you as undead. That game contains the most stylish undead in any game....
Personally, I don't see how being an obvious undead has any "style' to it at all in D&D - giving the Dm no real reason why your butt should be hounded by Radiant Servants of Pelor, clerics of Pelor, and for that matter any cleric or druid, anywhere, ever, endlessly.
Where's the style in loking like the Thriller video and saying, "Grr, argh!" all the time?
Anyway, the topic :
I play evil campaings constantly, and frequently play undead characters. My current one requires no level adjustments - I took a few levels of Vampire Spawn (everyone telling you to get Libris Mortis if you want to play undead is on the money IMO) in addition to being a Paladin of Tyranny- since the eventual stat boosts vampire spawn get increase Strength and Charisma, with a tiny boost to Dexterity to help out the all important AC, it seemed like a playable combo, and the d12 hit Points for being undead do not hurt a front line fighter at all - er, if you reached a level where you get more hit dice, anyway.
While only having one level shift is a good option, you can also only take one or two levels of this, never be a level lower than the rest of the party, still be undead, and still be able to walk into a town and do stuff without immediately being attacked because you are skeletal or look and smell like rotting tissue.
That option does have it's drawbacks, though, which this article goes into a bit :
http://www.wizards.com/default.asp?x=dnd/cwc/20051028a