We keep both pups crated while we are gone and at night. Min pins are known for their exploratory nature and we don't want them to find something they shouldn't when we aren't able to help them. We do occasionally let one or the other sleep with us, but they both tend to get restless in the middle of the night and go wandering. This means that one of us, often me, has to go track them down and get them resettled.
It took Mary awhile to warm up to her crate, but eventually she came to LOVE it. I feel like it marks a comfort level. Something along the lines of, "This is my bed, in my house, with my family." Anyway, it was a big moment for me.
I figured it out one night when Will kept running into the kitchen. It was close to bedtime and I had gone to brush my teeth, etc. He usually goes with me and when we walked by the kitchen door he seem more excited than normal and ran in there. I kept walking toward the bathroom, so he came back out. Then when I got up to put him to bed he jumped up and ran to the kitchen. I thought that he was going to his usual hiding spot (on the pedestal of our table), but he was in his bed. I couldn't tell for sure and had to put my hand in to find out. He stayed in and I told him goodnight.
I would love to post a picture of him in his bed, but I can't get a good one since he is so little. Instead here's a recent picture of the two of them: