Hit bulletproofme.com for some of the best explaination/writeup stuff I've seen.    You want some concealable level 3A, plus you want an outer plate carrier you can throw on over it.    For a higher-end solution, start looking at manufacturers' websites - they have some neat full-body solutions that the vendors (bulletproofme, etc) tend not to carry. Some of 'em don't want to sell to anyone other than police/military however.