I prefer road bike rides alone ... just the road, a tune on my ipod and bloody squirrells to swerve around.
however ...
I prefer off-road rides in groups, if you fall and hurt yourself deep in the woods some one is around to pick you up. But, I have done some proper solo epics in the past, 50 miles off-road with only a water bottle, a banana, no phone and 50p in my pocket.