The first and easiest use of tax-efficient Roth accounts is to indicate to the program whether you want to withdraw from the Roth first, last, or proportionally from both in the order of withdrawals. Typically it's best to allow your tax-efficient Roth to grow and use it last after the non-Roth retirement accounts have been used. But you can change the order of withdrawals in the Assumptions and Settings area to test this view.
MaxiFi will allow you to compare two or more IRA to Roth conversion strategies that you create and show you the impact on present value of lifetime taxes as well as the impact on annual discretionary spending and Medicare B premiums.
If you own the Premium or Professional version of MaxiFi, you may also use the maximization option to discover the optimal pattern of Roth conversions.