RMD question. Is it a good idea to pay more than the required RMD as long as I stay in the tax bracket I am comfortable with?

Required Minimum Distributions (RMDs) are the minimum that must be distributed from the applicable retirement account each year, and is generally considered taxable income. Any additional funds withdrawn are also considered taxable income, increasing your income tax. 

Withdrawing additional funds above the RMD amount does not have any particular tax benefit or penalty.

If you do not have an immediate need to spend the amount distributed in excess of your RMD, you would generally be better off making a Roth conversion of that amount rather than just taking the additional amount out and putting in in a nonqualified account.