While I never recommend sharing a cabin with a stranger to save the dreaded singles supplement, I also don't recommend sharing with someone you don't know really, really well. Even if she is your best buddy for movies and shopping, have you spent the night with her? Does she grind her teeth? Snore? Get up earlier than you do? Later? Is she messy, leaving her cosmetics, etc., all over the bathroom? Will she pack heavy and crowd into your space or pack light and want to wear your clothes? The same is true for guys. So be sure of who you are traveling with, because sailing with someone who has bad habits or traits you never knew about till you were on a ship can make for a miserable cruise.