Always okay, for sure, on another bike.

You know, if I was living in a city, now, I'd have no problem going even as big as a fat bike with the right tires as a utility bike. Those big tires are super comfy and fear no potholes, curbs, sand or road grit, rain, snow, you name it. My Pugsley would be a great choice. With racks and panniers, it would make a great errand/grocery store bike. It's no speed demon, but it's no dog, either, with the right tires. Figure you can only go so fast in traffic, anyway. A 29+ or 27.5+ would even be faster with many of the same advantages.

More snow coming, tomorrow! This has been one long and very snowy winter. Better get some riding in, today. Will probably be shoveling, tomorrow.