Audition help and suggestions.
After reading your post there are several things that come to mind and might help you prepare for an audition:
Sight reading is uber important. Most people say, "oh sure, I can sight read just fine..." but how often do you practice sight reading? This is a very very important skill that is absolutely necessary for passing a military band audition. I'm not sure how exactly the audition is set up for the Army bands but in the Navy band sight reading is HALF of your score, scales are 10%, and prepared solo is 40%. So if you aren't already working on this skill, I would recommend buying as many types of excerpts books as you can find and make sight reading part of your daily practice routine.
You asked what music you should prepare for the audition... well aside from learning as many band excerpts as possible and becoming a good sight reader, what solos do you currently have in your repertoire that you could prepare to a high enough level that you could play well in an audition? Anyone on this forum could recommend hundreds of solos to you, but that is a bit pointless if we don't the level/difficulty of the solos that you're currently comfortable playing.
Do I think that you should audition? Definitely, yes. Will you get in? I have no idea. From the information provided in your post it sounds like there is definitely a chance that you might have some improving to do, but then again there are a lot of really phenomenal amateur players out there who were never music majors in college. In the Navy bands if you audition and are not accepted into the program then you are required to wait 6 months before you can audition again. I'm assuming that the army has a similar policy, but it could be different. If you audition and are not accepted then it will probably be a very good eye opening experience for you, and will show you what you need to improve on in order to be accepted. I was in A school with musicians from the Army, Marine, and Navy band programs who all had very different musical backgrounds and experience, and VERY different levels of playing. There were a select few players who probably could make it in one of the premier bands, some upper level players, a LOT of average players, and a small handful of players who really shouldn't have been accepted... Sad, but it's the honest truth. I'm telling you this because I don't want you to be discouraged. I don't know what your playing is like so I'm not going to try to put you in one of the categories that I just mentioned. Take the audition and see how it goes... You either get accepted or you will learn what you need to do to be a better musician. Both are positive outcomes!
I have several questions for you that are mostly related to your post. You said that you have 7 years of expertise in total... I was wondering what constitutes that expertise? Does that mean that you've been taking lessons for 7 years, performing professionally (getting paid) for 7 years, playing in community bands for 7 years, etc...?
Are you currently studying your instrument with a professional teacher? If not then you should be, especially if you're preparing for an audition. It is important to have a set of well educated ears that can critique you and help you to improve. Also, what is your practice schedule like and how often do you really practice? Playing in ensembles doesn't count, I'm talking about real individual practice time on a daily basis. As you said in your post you don't have the years of expertise that many music majors have... so you need to make sure that you're practicing at least as much (if not more) than people who have many more years of experience than you if you are going to be competitive with them.
Gregory E. Lopes
Euphonium player
US Navy Band Great Lakes
US Navy Music Program, 2009-Present
Besson Prestige 2052