It's great that you are thinking ahead and considering how to optimize your Bitcoin spending strategy. It's important to keep in mind that there is no definitive answer to how much Bitcoin you should spend or hold, as it ultimately depends on your personal goals, risk tolerance, and economic outlook.
That being said, a million sats could be considered a reasonable amount for spending purposes depending on the price of Bitcoin at the time. However, as you noted, transaction fees can vary and may necessitate larger balances if they become prohibitively high.
It may also be worth exploring privacy-focused solutions such as coin mixers or off-chain transactions like Lightning Network to help further protect your privacy when making transactions.
Ultimately, developing a well-considered strategy based on your individual circumstances can help ensure that you're getting maximum value from your Bitcoin investments. I hope this helps!