As promised -- sorry for the wait --
But she has been seeking out rich and noteworthy people lately and occasionally neglecting her less 'important' friends, which is not cool.
And she didn't used to be like this which is why it particularly annoys me - I thought she was more sensible than that. Perhaps it's menopause?
No enthusiasm is not the problem.
Hmm, it's something that's difficult to explain I suppose. I'm not opposed to being proud of one's kids or excited by what they do (it's rather lovely actually). It's when it becomes a superiority thing; like she's wanting to engage in a pissing contest totally assured she'll win (because that's what it's really about, her).

This is the sort of situation where I'm not sure how to respond, because obviously there's all this background information on her that you're basing your judgment on, that I don't have. What's your base knowledge here? How did you come to the conclusion that she's only seeking out these people because they're important or high-class -- and how do you know that it's arrogance and not just enthusiasm? I know that I should trust your judgment, but the only thing that's throwing me off is that the examples you mentioned earlier seemed pretty normal and non-annoying, out of context, and I related to them. Sometimes people think I'm bragging when I'm talking about cool things that have happened to me, when all I want to do is share my excitement.
Assuming your intuition is correct (which it probably is): is there anything that's happened in her life recently that would lend itself to a shift in focus for her, from not caring about status to caring about status?
No, she wasn't fully intending on following through, but she talks about it as if she totally would. It's just strange how planned out and seriously she takes even a hypothetical situation - and how much she then falls in love with the idea and then begins to think it very practical and devoid of any possible flaws.
^ That's weak Ne, is what that is.

That's an Ne-Te loop. Although I do relate to the bolded, on a basic level. The part after the bolded, I don't relate to; in fact, it doesn't even make sense, when keeping the bolded in mind.
I say that because when an ESTJ hears about a possible new thing, this is the process they go through:
1) Suspicion. What the hell is this? How does it work? Are you SURE that's how it works? Find me some credible sources!
2) Ne/Fi kicking in. Whoa, that's pretty cool! The ESTJ starts to idealize the new thing, thinking of only the problems it solves, the things it makes more convenient, how fun it is to use, etc.
3) Si and Te restrain the Ne, and force the new thing into the ESTJ's mental network/ranking system. It may be cool, but is it cooler than any other similar thing you've seen? What are the pros and cons?
An ESTJ would never find something practical if it isn't, unless they were given credible information that led them to believe that it was practical.
Thanks for your answers BTW
No problem!
Yes, ESTJs are so passionate when they're pissed off and people tend to write it off as crazy ranting. They don't seem to have much self-awareness in such a moment and aren't as able to edit the expression of their feelings or tone down their intensity. I feel so bad for my sister because ever since she was a kid, she was teased for this. This is partly related to my national culture, which strongly emphasizes temperance and a laid-back demeanour; so being fervent and passionate is frowned upon, ridiculed even. She blows up about something not being fair, for example, and people laugh at her reaction - then she gets even angrier and they mock her even more. Eventually she becomes quite upset at being so devalued and misunderstood. I really sympathise with her frustration - it's really horrible to have your perspective undermined or to have your emotions dismissed

. She has become a lot better at keeping her temper, though (working in hospitality will do that - nothing tests one's patience more

). I must say however, I do admire her butt-kicking ability in general. While people like me dilly-dally or just put up with crap, she's taking action and speaking up for what is right.
I think the whole thing is made worse when you're a woman too. If a guy does it - he's considered a bit overly aggressive (which lets face it, most societies don't consider to be all that negative). If a woman does it - she's a crazy, psycho bitch.
SO TRUE. ALL of this. And omg i can only imagine what it would be like for your sister in that situation. That would be so, so horrible. I've been in similar situations when people undermine me over and over and over; usually I'm not easily enraged, but if I was in your sister's situation, I would probably either burst into tears, or fly into a rage -- "God damn it, shut up! Where is your respect for me?? I would NEVER treat you this way. HOW DARE YOU!" -- and that would just make me seem crazier, probably.
And the gender thing is something that I've always found frustrating. A consistent wish of mine, ever since grade school, was that girls could be as "badass" as guys without the negative connotation that comes with it.