Don't worry about the carpet. All event centers and many churches have hideous carpet so it won't show the dirt and wear. There is little you can do about it and nobody expects your wedding colors to coordinate with the carpet, they won't even be looking down.
Since you have "mocha" in your dress beading...it is pretty popular now to do a chocolate and accent color wedding .. chocolate and aqua (or baby blue), chocolate and light green, chocolate and pink, or purple, or yellow, etc. You get the idea. It can be a pastel or a bright (hot pink for example).
The BMs could wear chocolate and an accent of your other color, or reverse. It would be great either way and would pick up on the mocha color of your beading.
I knew I loved hydrangeas and wanted to have them as my flower and theme...it was just a question of purples or blues, eventually I went with purple and lavender as my colors. Seemed very "wedding-y."
Since March is pretty much spring, you can use pastels and not worry about choosing colors that seem too "autumn-ish" or coordinate with your ceremony or reception site.