My dogs have always had a toy or something that they like better than others. My current two and two of the last three ... wait, that sounds confusing. I had three dogs that essentially grew up together. It started with my beagle, Katie. She needed a puppy, so I got her a golden retriever. "Katie, this is your puppy." Well, she understood, and so did Tina, the puppy. They were inseparable. Then I was chosen by Stanley to be his adult. Stanley bonded with Katie and Tina. They were soooo close. They all died within 1 year of each other, and Tina actually had a traumatic negative reaction when Katie passed. Seriously, she went blind and deaf almost immediately. She just missed Katie so much. Anywho, they were each other's comforts.
Now I have two dogs and for the first time, they've been crate trained, and they love that crate. It's open for them, and that's where they go when they want private time or alone time. It's their special place.