If it were me I'd do advantage and think she should too for various reasons. She actually does have a summer job if she wants it.
But she has her reasons for wanting only shorter program. I shared what 'advantage' actually meant. She'll need to decide this one for herself.
I will add some further information for some people.
Some of the potential downsides and upsides of staying for 7 months:
You're away from family further and you're locked in. If you don't like it and your role, you have a longer program. It also means you lose chances during the summer. However, people who do the 3 month program usually don't form the same bonds as the people who stay for 7 months. The managers, I worked at one of the largest locations, started to get to know me better around the 3 month mark. I also noticed those who stayed for the advantage program formed closer bonds and had better potential. You can also take Disney classes during the first 3 months and have freedom during the summer if you wanted to do that way.
However, the way I view it, in reality we're all going to be living away from our parents. These 7 months teach you a valuable life experience, you live a sense of freedom you will eventually have to deal with on your own - except you have a safety net. You're surrounded by thousands of other CPs who are in the exact same situation, you have guaranteed transportation, albeit not the most reliable, and you have people all in the same situation as you.
It is a test trial and teaches you quite a bit about yourself. The other advantage of advantage is if you extend, you're there for a year. The other way extensions would work if you decided you wanted to extend is you extend to the advantage and then to the 1 year. Extensions are tough to get, having a longer period to prove yourself will help with a career. Not to mention it looks better on a resume to have 6-7 months versus 3 months.
There are downsides and it depends on what their plan is. Disney isn't the highest paying job but the experience is worth it. I just had a call, the other day, specifically referencing my Disney experience. It makes a difference.