It's a small one, but there was an episode where Hyacinth was speaking to a socialite who was, somehow, even more obnoxious than she was. Said socialite flat-out insulted Onslow and Daisy; although it lasted only a second, Hyacinth's Death Glare reaction shows that in spite of all she says and does, she truly loves and cares for her family.
The conclusion of the Cruise arc. Hyacinth assumes Onslow and Daisy snuck on to the same cruise Richard and her were on when they had really won a trip. After spying on them the entire trip, once the truth comes out, Hyacinth watches Onslow dance with the captain's table. She gets up and asks to dance with him. They end up getting a roaring applause from the crowd. It is a hell of a Throw the Dog a Bone moment for people who root for her.
Not long after Richard retires, Onslow gets so concerned for his well being, now that he's around Hyacinth 24/7 that he evidently has nightmares about the poor sod's fate. He then visits Richard, taking him on a trip down to the local pool hall to show him "the joys of irresponsibility." It's one of the few times we get to see Richard loosen up a little, and shows that despite the rough exterior, Onslow's really a pretty nice guy.