How do you get a 19 before racial adjustments?
If you're getting a free LA +4 and can have spellcasting but nothing too high-level, I'd consider making a warrior type lich. Maybe a duskblade or something, though psychic warrior could also work. Something heavy on Cha (paladin of tyranny?) would be good if you want to pimp out your paralysis attack. If anyone asks, you used to be a much more powerful spellcaster, but after you achieved lichdom, you used one of those fake-being-alive spells and had a wight buddy drain off those levels -- being a full caster was only a means to quasi-immortality, not something you wanted to spend eternity doing.
Getting the cost of the phylactery past the DM might be really tricky, though. Maybe you don't HAVE your phylactery, and that's why you're out adventuring -- it's gone missing and you're trying to find it before it's destroyed, or possibly you know who has it and they're holding it as a blackmail threat over you to control you, for now.
Lich is pretty damned tough, you get a host of immunities plus pretty big damage reduction. None too shabby at sneaky-type infiltration either, you get a racial bonus of +8 on Hide, Listen, Move Silently, Search, Sense Motive, and Spot checks.
Shameless replug of a build I'm using right now, copy pasted from another thread:
The Shadowbane Inquisitor PrC from Complete Adventurer is amazing for the Fallen Paladin route, because A) the class is very interesting (zealots who believe it's okay to sacrifice the innocent to prevent evil) and has the potential to be TERRIFYING if Fallen, and B) Shadowbane levels stack with Paladin levels to determine what Blackguard bonuses you get for Falling, but you don't actually lose any of your Shadowbane abilities for turning evil, as the first level ability Conviction lets you keep them no matter what. This can get you a pretty crazy Sneak Attack, 4th level Blackguard spells, and a high BAB. Build would be something like...
Rogue 2/Paladin 4/Shadowbane Inquisitor 8, then at this point become a Blackguard and convert all of those paladin levels to Blackguard, ending as a
Rogue 2/Shadowbane Inquisitor 8/Blackguard 10. +19 BAB, 4th level Blackguard Spells which can be DMMed (though you mentioned not wanting to do that,) a Smite that can be used on anyone, and 7d6 Sneak Attack.
If you wanted to do something really bizarre, the character I'm playing is actually a slight alternate of the above because I wanted to do something slightly different...He's actually a Rogue 2/Shadowbane Inquisitor 7/Blackguard 7/Lich +4 LA. This knocks you down to +15 BAB (though if you go epic one level, you'll get that last BAB), 4th Level Blackguard Spells, and 6d6s Sneak Attack, PLUS he's an undead, incorporating all the immunities and bonuses that includes. You can DMM the 3rd level Blackguard spell Fangs of the Vampire King (SpC) to get a free Natural Attack, which the Lich can channel his Paralyzing Touch ability through. A Full Attack would be 3 Power Attacked swings from some scary 2hander, Sneak Attack damage (this guy actually has great hide/move silently, and can summon things to flank) followed by a Negative Energy bite from the fangs that drain 1 Constitution and forces a DC 31 Fort Save or they're paralyzed. (10+ 1/2HD (8) + 13, assuming a 36 CHA). Throw a ring of Positive Energy Immunity on him to be really unpleasant.
Of course, with your LA +4 for free, you could go with the former route listed above and still get the lich goodies. Actually, if you take 2 levels of Paladin of Tyranny or Slaughter instead of Blackguard 9-10, you gain your Cha to saves again, meaning x2 CHA to all saves, and only lose 1d6 Sneak Attack.