Tarpley, something else to consider.
What is the bonus based on? Solely on your performance, or on your company's performance as well.
In the case of mine, it is based half on my performance, and half on the company's performance vs. their target earnings number for the year when they report fiscal earnings to the SEC. If we are under/over the target number our bonus is decreased/increased by a similar percentage. Because of that latter basis, our bonus is treated not as standard wages for witholding, but as short term capital gains and the government is going to take about half of it regardless of how many exemptions you claim.