Is a Roth conversion an optimal strategy in my situation?

My wife and I are 73 and 75 and in RMD territory. With pension, SS and RMD our marginal tax bracket is 24%.

80% of our assets are in tax sheltered IRAs. Other than QCDs to reduce tax liability are there any other strategies? We recognize that one of us will be facing the widow/widower’s tax situation. Also IRMAA will take a bigger chunk of our Medicare bill.

My feeling is that we continue with our current situation and pay the effective tax rate of maybe 18 – 20% going forward. But I can be persuaded to do otherwise. Your feedback is appreciated.