A few random thoughts:
1) I suggest thinking of miles/points as a currency instead of "free travel". At a minimum, the value / opportunity cost of using miles is equal to what you'd get by using the miles to redeem for gift cards or merchandise (these options tend to offer terrible value, but using a near-cash redemption option as an example, miles have a minimum value of 0.3-0.5 cents per mile).
2) There are many different ways to approach your situation, e.g.
"I want to use miles as much as possible even if the value isn't great."
"Where can I realistically go using my miles?"
"I want to go to xyz. How can my miles help me with my trip?"
It may make sense to spend a little time thinking about your priorities...
3) In your case I'd argue that the best strategy will likely involve using miles and cash. Or to put it differently: How can your miles reduce the cash cost of your travel, while maximizing the value of your miles? E.g. instead of spending $25k for four business class tickets and ten nights at a 5* hotel, it may be possible to book four business class award tickets, thereby reducing the cash outlay to, let's say, $8k. Or you may want to go to a destination with very limited award availability: Consider booking two award tickets and paying for two tickets out-of-pocket.