The other one, Lily, (actually named Lilybelle by my mother), loves to have her butt rubbed. She purrs and purrs like mad whenever someone itches her rump. Many people are surprised, it seems, by the variety of different sounds (with correlating meanings) guinea pigs can make.
Lily sleeps on her side, and doesn't close her eyes, which has startled me a few times - Imagine walking in a room to see your pet lying on its side, legs sticking out, eyes wide open, not responding to external stimuli?