How to manage large IRA balance. Confirm large annual withdrawal rate. Would like advice on high value nest egg.

Let me start by saying I have been lucky.

I have $5m nest egg 85% is traditional IRA, 7.2% Roth and the rest post tax brokerage. We are 64 & 63 and plan on collecting SS of $69K at age 67. Because we are so IRA heavy is seems we have no IRMMA or tax strategies to exploit. We must withdrawal from the IRA and get taxed. It looks like I need to withdrawal around $250k annually to do any kind of RMD management. If that is what we do I will do as much Roth conversion as possible (this will be the kids inheritance). Fortunately we are in a state that does not tax IRA or SS.

Does this sound right? Is there any other strategies I can employ.