We went tent camping last week, first time in a while.  Waaayyyyy too warm for our 20 and zero degree mummy bags, so we just used one of my old poncho liners.  Perfect for the low 50's (give or take a few degrees) nights here in the Pacific NW.  Along with a little snuggling of course.
Side note: my old (bought in 'bout '88 or 89) little dome tent finally blew out a zipper.  Gonna have to look for a suitable replacement now.  Lotsa memories in that tent...
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OBG