How much did your Roth conversion cost you?

I am deciding whether or not to convert. I will be working for at least 10 more years. By then my tax-deferred funds will be slightly over $2 million. I want to convert at least $250k over a 5 year time span in my working years. Did anyone convert during high earning working years?

My main concern is, if I die, I don’t want to leave a taxable legacy to my daughter. Would that be bad? Maybe I am making it sound worse than it is.

I will be 52 in January and want to be “work optional” by 61 or 62. Plan B is to convert nothing and just live off tax deferred funds until 70.

For context I have a brokerage account of over $300k and Roth funds of $200k right now. Any feedback on converting?