I want to second the RRG, KY as a great place to go see the stars. I would recommend you go to the lookout "cloud splitter" great views in all directions. There is also a back entrance to a "secret cave" you can climb through and explore. The cave ends at a big opening in the middle of the cliff and makes for a cool photo (You can see the cave opening at the 1:05 mark in the video). Only about 1.5-2 miles from trail head. Of yeah, and for the love of God please don't carve your name in the rocks! Just because countless assholes have been doing it for years does not make it ok.
https://www.youtube.com/watch?v=BqvCvMHpKIg