Actually, a good point about vampire LA is that it's really hard to quantify: I think the designers really just picked something that "felt" right. Technically, I would say that vampires have much higher than a +8 LA, but their weaknesses knock it back down. I'm sure I've done this before (and on these boards, no less), but I think I'd break it down something like this:
- blood drain: +.5
- children of the night, spider climb: +.5
- dominate: +1.5
- create spawn: +2
- energy drain: +1
- alertnate form, gaseous form: +.5
- DR: +1
- fast healing, including the fact it can't die from HP loss: +2
- resistances, turn resistance: +1
- stat boost +1
- skill boosts, 4 feats: +1
- garlic, mirror, and holy symbol aversion; running water limitation; can't enter unless invited limitation, vulnerability to running water, vulnerability to stake while helpless: -1
- sunlight vulnerability: -3
Some of those are basically "rounded," but I think that's relatively fair.
I agree with Drowbane, though: the permanant and wide-ranging nature of the create spawn ability - not to mention the "pyramid scheme" that it can create - make it an incredibly powerful tool in the hands of a PC. Only the vulnerability to sunlight keeps it from being game-breaking with vampire PCs; without that, you've really got a potential for abuse.