All....they can give out multiple nominations....
Here's a little story, and not the most advisable route....
I had applied to USCGA, USMMA, and USNA. Of course, USCGA didn't require a congressional nomination, but USMMA and USNA did.
I had an interview with my Congressman, and Senator Bill Frist. I quickly received a letter from Senator Frist about USNA. A couple of weeks went by, and not sure why I hadn't received a nomination for USMMA, I called and asked his staff member for a nomination to USMMA as well (at this point, I wasn't sure which academy I wanted). Well, they did it, so I have my USNA and USMMA nominations, but from Senator Frist. Maybe a week later I get my letters from my congressman, which were the nominations too.
As soon as I figured out I wanted USCGA, I notified the other two academies, and I had nothing but positive things to say about them.
Later that year, while serving on an advisory board for the Health Department of Davidson County, Senator Frist came to speak to us. After the presentation, I thanked him for the nominations, and believe it or not, he not only remembered me, but also my decision to go to USCGA.
On a side note, and this is about the interviews, definitely do your best. You never know who you're going to talk to. Be honest.
For my Frist interview, I had a staff and a Navy commander in my interview. I was honest that I was leaning towards USCGA but hadn't made up my mind completely, and that I was also looking at USNA and USMMA, and had a NROTC scholarship as back up. They asked where I had applied for the NROTC scholarship and I told them Vanderbilt, UNC Chapel Hill, and Auburn. When asked which I would be my top pick, I didn't hesitate to say Vandy.
Little did I know, the commander was actually the CO of the Vanderbilt NROTC unit. Without having to complete an interview, I had been accepted to the Vanderbilt NROTC program, confirmed by a letter a week later.
You tell them what you want to tell them, not what they want to here. When asked if I was ok with going to war "I think that's where we're headed. Someone's going to kill bin Laden, and I think it should be us." Direct? Probably, but I think it was a clear enough answer.
Interviews will also vary. Frist was a two person interview, but for my congressman, I was stuck in the middle of a semi-circle made up of 15 people firing off questions for awhile.
Panelist Question: You're going to be yelled up by upperclass, do you think you can take that?"
Answer: "My mother's been yelling at me for 17 years. I don't like it, but I will live with it."
