Everyone sucked up to Darcy because he was rich, but Elizabeth judged him by his attitude and behavior, not by his bank account. He wasn't used to that, it was unique in his experience. When she does start to like him its not (as she jokes when she tells Jane about her engagement) after she sees his beautiful grounds at Pemberly, but after he goes out of his way to help her family out of what was an embarrassing and potentially devastating - from a social point of view - situation.