Even when I had a bag, I would unzip it and lay under it instead of getting in. If you've found yourself doing that in the past, or if you find yourself restricted by a traditional bag, you'd probably enjoy a quilt. I'm typically a warm sleeper and have never been cold, but can see how that would be a concern if you're not a warm sleeper.

I bought one of these to go over my sleeping pad and it's been great.