We have four in the house now, although one is a friend's dog who is staying here while she's travelling. It can get a little chaotic at times, especially when the someone comes to the door, but if there is one thing you can do to instantly improve your quality of life, getting a dog is it.
We've kept a friend's dog whose owner has traveled in the past. The dog is inconsolable for a couple of days and then she adapts to her new family. Her bed is kept in the bedroom. So, she doesn't feel alone. Once, when I was sleeping, she came to me and barked. I woke up almost instantly, looked at her, realized that she wanted attention, and obliged in my groggy state. She wagged her tail and went back to her bed.
I was dozing off when I opened my eyes again, and said, "Wait ... did you just wake me up ... so that I would pet you!?" Cheeky monkey!
I did feel sad when she went back to her real family.