Sierra Designs Pull On Down Bootie.
Why are they so great? Because they will keep your feet warm and toasty and not take up much space/weight in your pack at 11 ounces. Even if you're car camping, the less you have to carry, the better. For a long time I was using my Acorn Summit Slippers and they were great, though too heavy to consider taking on a backpacking trip, they were fine for car camping. As they wore out I bemoaned the fact that they're no longer available and wondered if I'd ever find camp slippers I liked again.
The Sierra Booties are actually an improvement because they are more versatile being much more suitable for travel and backpacking. They're 700 down fill, making them light and warm. The bottoms have a non skid sole, and the cuffs are fleece lined and adjustable. They feel so good on tired feet, and they are cushiony, which is revitalizing. I would not wear them in muddy or wet conditions, you'd wreck the bottoms and down isn't meant for that but if weather is wet, they're still great for inside the tent. You can really drive up your comfort level with minimal effort here. They're even machine washable (front loader only) for easy care. I Love these booties! Find them HERE.