If the Miss Dashwoods were elitist, then they would be like their brother, and not care about the vulgarity of Mrs. Jennings, or the insipidity of Lady Middleton; they would welcome their attention with honor. At this point, they dislike Lady Middleton; not because she's not good enough for them, but because she has nothing to recommend herself with. They are liking Mrs. Jennings, because they see her sweet spirit and kindness.

The only elitists I really see in the book are the Ferrars'. They won't let Edward take the cloth because it is not fashionable for them. They want him to marry Lord Morton's daughter to secure a title in the family line. They dislike Elinor and Marianne because a) they feel that Elinor and Edward are attached and b) because the Dashwood girls are basically penniless and therefore useless when it comes to meeting the first families and dining in the first circles. In fact, they seem to (by what I can see at this point) have an idea that the Dashwood girls would hurt their chances of invitation into those circles.

I don't hold it against Marianne and Elinor that they want smarter, better company than what they have, and perhaps Marianne is not quite as grateful as she should be, but Elinor works with what she's been given, and Marianne is learning.