Mine aren't too bad about me leaving, but then I always deliberately take time to stop what I'm doing and spend a few minutes with them, look each one in the eye, telling each one how I missed them and how I'm so glad to be home.
People would probably think I'm crazy, but it does help to keep them from getting too down in the dumps about it. DH says they're fine when I'm gone, no problems. But because of how stress can affect them, it's worth it to the 'Aw poor baby, Mommie is so sorry' routine to get them back into their routines as quickly as possible.
My Peek a Boo is the worst. I watch him for the first few days I come back from vacation, and I'll stop what I'm doing especially just for him and just hold him or rub his tummy and talk to him, and give him kisses. I'll kiss one side of his face and he'll turn his head so I can kiss the other side.
He gets as many kisses as he wants (part of the deal after I adopted him), then he'll give me a kiss or two, and I ask him 'Are you okay? You know Mommie loves you. Did you get enough kisses? You can have more if you want. You know you're my boy, right?'
And when he's done, he'll start play biting my hands, and I say 'What! Are you biting your Mommie! Oh my goodness! Oh he's playing!' And he gets so wound up, it's so funny. Then he lays down for a nap... and I know he's allright with me. That's my boy!