"Mr. Collins appears very fortunate in his choice of a wife." (Chapter 32)

How about this: Since Darcy has come to Kent he has behaved a bit better than appropriate. He visited Charlotte the morning after his arrival which she believes is a compliment to Lizzy and not necessarily to herself although it does come to light in Chapter 32 that Darcy has a good opinion of Charlotte's abilities. Charlotte may feel her personal connection to Lizzy rather than Darcy’s regard for Mr. Collins could be an advantage and perhaps someday benefit her family. If Lizzy married Darcy, any livings he will bestow could conceivably be given to the son of his wife’s friend if that progeny stuck him as favorably as the mother. Charlotte could also be thinking of her younger bothers who will need professions although if any of them are intelligent enough to impress Darcy is another matter altogether. IMO it is most likely Charlotte is thinking of her own children’s future but there is no telling when good connections will come in handy. I think Charlotte has a mind which naturally and immediately searches out the advantages of a situation for her family. ;D