I have no love for the character Betty, and I think people who find January Jones hot mix up the character and the actress. The character is selfish, childish and extremely maddening. I did appreciate how she let Don come see his son on his bday after all, but since it's what she should have done in the first place, hard to give her credit for it. That's like giving a guy props for paying child support and not abandoning his kids ... he's SUPPOSED to do that.
As for Joan, she didn't need to be so y, but considering her hubby is about to go to basic training (and then likely off to Vietnam), I can cut her some slack. If she had been in a better mental state, she would have handled it differently.
But I think her relationship with Peggy has always been complex, and it's not as easy as just calling her a . I think part of her wants to help Peggy by giving her tough love (not unlike Don) and the other half is probably jealous of how Peggy got out of the secretary pool. Put those two dynamics together and you are going to have fireworks sometimes.