You can rent a hotel room when your 18 right?

No. Many major hotels require that at least one person in the room be over the age of 21. I have a young woman working for me that has found that out the hard way on two separate occasions and she was with her husband. Neither of them is 21. To top it off, she is in the military. She burst into tears and said, ';I can die for my country, but I can't go to a hotel with my husband';!