It's not really a set amount so much as a familiar relationship with an SA.
You may also find this thread useful:
http://forum.purseblog.com/louis-vuitton/how-to-become-a-lv-vip-15441.html?highlight=vip
You're right that it's not about a set amount that you spend.
But it's also not about having a relationship with an SA.
You basically get selected when you fit the clientele type they are looking for. They'll see you, you can't just 'work' your way into the title.
In Michele's case for example: They obviously saw a young, beautiful lady that had a sense of style and that for them is the type of client they wish to have projected out unto their clientele body. For people like Michele, the rule is do as much as possible to maintain her as a content client because it just looks good.

Sorry, but if you just doesn't 'have the look' then really being 'nice' with your SA is cool and all, but it doesn't mean much.

VIP status means you get what you want when you want it. I.E., once in season items come in and they claim they're sold out, they've secretly reserved a bag just for the VIP which no one can touch. They reserve rare items for VIP's without even asking them, as a simple courtesy should they request it or when they fone them.

You also get invited to the shows in NYC or Paris. Flagship stores in NYC and LA also have a special point person that deals with these high value, high priority clients.
In-store showings are not really VIP events as much as they are normal events with a select body of individuals that may purchase a particular line, item.
I didn't read the above thread but I've already talked about this sometime before and I'm just paraphrasing what I've said before.
