I prefer Cracker Barrel over Wal-Mart, they tend to be further off the road and quieter. On the other hand, Wal-Mart probably has better security. I have occasionaly used truck stops also and felt quite safe there. As for why, generally it is just for time savings when I have a long ways to go and can't find a campground near where I am when I get tired. Plus, if I wake up in the middle of the night ready to roll I don't bother anyone by leaving during quiet hours. I always try to leave the host clean and spend some money there.
