The previous posts on this interview are pretty much spot on. I attended a group interview in Denver that had around 60 people there. After the Skywest members spoke for about an hour on what is expected of the position there was a 15 minute break where maybe 20 people left. Then came the part where every person had to give a one minute speech on why you would make a good flight attendant. Here, I think the most important part is being confident, coming off as approachable, and saying something that is memorable. Also, make sure you dress appropriately (business suits). All the people who were given one on one interviews made speeches that caught my attention, whether they had previous flight attendant experience or not. The one on one interviews were not overly stressful, asking mostly situational questions. After the one on one interview, I heard I had been offered a position two weeks later.
I think it is important to note that the training class you would have to attend if you are offered a position is about a month after the interview. My group interview was held on April 21 and the training you had to commit to attending started May 20. I was not aware of this and, though I received an offer, was not able to accept since I could not attend the training date.