Enjoy another silly monster manual picture! Seriously, that ghoul would be pretty freaky-looking if at least it wasn't purple.
Ghouls are about the weakest undead in the entire book, ranking just above zombies and skeletons in strength. Despite this, Libris Mortis put ghouls at ECL 5 (thanks, WotC!).
The undead got decent stats all around, with +2 or +4 to every ability (except constitution, obviously). They also possess some turn resistance (it'll be needed), a decent bite attack, and two claw attackss that would be forgettable if it weren't for one minor ability.
Said ability? Paralysis. Every non-elf hit by either attack needs to make a fortitude save or lose two to five rounds of actions. This means a ghoul is essentially forcing three save-or-loses a turn: quite impressive!
Finally, ghouls can also inflict creatures with ghoul fever, a disease that would be useless if it didn't have the ability to turn humanoids into more ghouls (which apparently causes gnomes to stretch and half-minotaurs to shrink). As it is, it'll probably has some niche use in giving the party cleric commandable foddler.
This may seem pretty hard to rate, but fortunately there's something out there that gives almost the same: the gravetouched ghoul template! Upon comparison, gravetouched ghoul gives racial traits in addition to its usual benefits, an extra feat and stronger claws. As far as I can see, gravetouched's +2 LA is considered pretty appropriate.
Considering all that, I'll give ghouls +1 LA. They'll have the same BAB as a level 1 gravetouched ghoul fighter/barbarian/warblade, and in exchange for giving up some of GG's goodies get more HP and smarts, as well as a better HD situation (an initiator level, for example, is better on a regular ghoul than a gravetouched one).
Lacedons are basically ghouls with a swim speed and the aquatic subtype. The latter is pretty pointless on something that doesn't have to breathe anyway, but it may make them vulnerable to desiccation-based spells: check with your DM. No LA change needed.
Natural attacks bumped up a size, more natural armor and better ability scores topped off with the ability to sicken people (more-or-less duplicated by a mediocre feat). I don't think that's worth two extra undead HD and the lost ability to go lacedon. +0 LA.