I am listed as my boyfriend's significant other and have the same benefits as I would if I was his wife. I've gone on two trips with him. One to Las vegas and one to Atlanta. Its nice when you have the whole day to walk around and hang out. The only thing you have to make sure of is that the flight isn't oversold by too much if you dont live near the airport. You don't want to fly all the way to Atlanta and not get on
Although, when I went to Las Vegas with him the flight departed at 7:30 on a Friday night out of FLL and was oversold by 10, and I was like #5 on the non-rev list. Who would have thought it, but I made the flight! So find out what kind of benefits you have, look for a trip with a long overnight and don't let oversold flights get you down : ) Have fun!