I don't have pets because I'm often gone, and I wouldn't want to leave them. I like dogs, I like cats, I like most critters*, although I've never really wanted a pet tarantula. (But I'd pet-sit for one.) I have vicarious pets, and I enjoy them very much. And no, SINS, Alice belongs with you. ;-) There's something comforting about pets, and I know there have been studies (too lazy to go look for them) on how they lower stress and blood pressure, and patients with chronic pain feel less when petting a dog or cat.

*Have had pet rats, mice, cats, a dog, lizards, and enjoyed hand-feeding wild birds and chipmunks. And fish, but I won't count fish because you can't hold them in your hand or let them sit on your lap... at least not for long.