A loving couple, the Rostovs are the heads of a functional and happy family. Their main problem is Count Rostov's total inability to manage money.
You know what we realized when reading War and Peace? There are very few happy, normal, affectionate families in novels. Seriously, think about it – any come to mind (aside from the Weasleys)? No, because of course, conflict and unhappiness inherently have a lot more drama. But here, in the middle of this sprawling work, you've got a totally reasonable picture of a family unit. Parents who love each other, and who also love their children. Brothers and sisters who get along, who are friends as children and later as adults. Sure Count Rostov isn't the world's greatest money man, but still, with the kind of family he and his wife create, that seems like a forgivable flaw.