In the absence of rain or bugs it's the only way to go. I cowboy-camped for a total of seven nights in the Grand Canyon last summer. I had a tarp that I set up a few times but never got under it. I'm addicted to starlight so don't like to be under tree cover if I can avoid it.

I have one anecdote regarding condensation: a while back four of us were camping near Sandia Peak outside of Albuquerque. The weather when we went to sleep was clear and the stars were great. I was outside in an old 45-degree bag and a homemade Tyvek (the clothing kind, not crinkly house wrap) bivy. The bivy has a large floppy section that I can pull over my head like a blanket. My sister was also under the stars and two others were under a tarp. In the morning it was chilly and there was a lot of dew on everything including the top of the tarp. My sister's bag was completely saturated. It weighed it ton. My bag was perfectly dry, even though I had pulled the Tyvek over my head sometime during the night and had been breathing into my "sleeping system" for most of the night. The fact that I was using a light sleeping bag (barely sufficient) may be important: I don't know if I would have stayed as dry in a heavier bag without my body heat escaping and taking moisture with it.