Right now I'm a sophomore in high school and am looking to build up a repertoire for college auditions. Almost every school I've looked at wants a Bach, and I have the Prelude and Fugue (currently working on the Allegro) of the BWV 998 worked up to where I'm pleased with them when I listen back to recordings, so I should be okay there. Places like John Hopkins and Oberlin want two or three "contrasting selections," and for these I'm looking for suggestions (I figure that even if I don't make it into a top music school like that, it couldn't ever hurt to work up the material on those repertoire lists). I'm thinking a Villa-Lobos Etude wouldn't be a bad idea, just to show that I've done one, but, like I said, I'm open to suggestions.
I would suggest some more contemporary pieces. When I was looking to audition for conservatories, Oberlin being one of them actually, I had the Koyunbaba Suite and the first two movements of the Stele suite in my repertoire for contemporary pieces.

Villa-Lobos and Bach, while the are good composers, are incredibly overdone. How are you going to distinguish yourself?
My God, it's full of stars!
If you can play BWV 998 musically and you haven't even graduated high school, you are already good enough to get in pretty much anywhere you want. BWV 998 is usually reserved for 3rd year and above as far as I know so if what you say is true, you show tremendous amounts of promise. You should really consider auditioning for the conservatoires in Europe if you are already that good. You could easily get a scholarship if you nail BWV 998 and whatever else you pick at the audition.

As for other repertoire, you could have a look at some Dodgson, Gilardino, Bogdanovic and a bunch of other contemporary composers but those would happen to be the more 'guitaristic' composers that came to my mind first. There's nothing wrong with doing Villa-Lobos if you do it well. College/university audition panels aren't looking for perfect players or anything, they're looking for potential and an obvious passion for music and playing the classical guitar. Want to impress the panel with Villa-Lobos? Learn Etude 10, it's not played often (you'll see why!) and really demonstrates a very fine control of your instrument if done well.