I never spend points on high category hotels but have sometimes spent points and cash on those
(fx Hilton Tel aviv, 28.000 points + 125$ - instead of ~400$/70.000 points).

I spend points on low category hotels, often in combination with 5th night free (fx. Hilton Sibiu, Romania 40.000 points for 5 nights, Doubletree Bratislava, Slovakia 40.000 points for 5 nights, Hampton Inn Krakow, Poland 20.000 points for 5 nights).

I have never spent points on middle category hotels as cash always seem a better value for me (if I avoid especially expensive days/periods).

In general, I prefer spending cash as I like earning points but on the other hand I don't want to hoard points.

I also book very early, take full advantage of sales, am very flexible timewise and location wise so I tend to get very good cash prices at the hotels I stay at.