Not an owner yet, but the stocks I own I usually reinvest into my next stock purchase which is sometimes a different pick, a leveraged ETF at times. I'll take the money if needed. I have Scottrade and they don't reinvest. I always deduct the dividends from my cost in my stock tracker.
Deducting dividends from your cost is not correct if they are paying you cash. If you broker does not reinvest fractional shares like most do. Get another broker. This shows they resolve conflicts of interest in there own favor.