Dale, do you have a particular temp range you're aiming for?
I've slept out lots of nights either just in my clothes, or inside a light bivy with no quilt or sleeping bag. The most helpful thing I've found is to have enough insulation under you to keep the ground from sucking all the heat out of you.
When I travel I occasionally like to be a hobo, so I'll take along a BPL torso pad, a polycryo groundsheet, and a poncho tarp. I wear as much of my clothing as I need for the conditions, and find that light gloves and an appropriate hat are wonderful luxuries that don't take up very much space.
If the trip is wilderness focused then I'm usually happy for the comfort a light quilt can provide, especially for those nights that are colder than expected.