At most, I'll sketch a layout of an area. I almost never use a proper battlemat, and I don't think I've ever used minis at a game that I GM'd. I'll certainly spend a lot of time on my overland maps, and I am learning some appreciation for interior mapping thanks to the challenges.

I am solidly a narrativist game master, favoring social interaction and cool cinematic action. Projecting a battlemat or VTT surface wouldn't really help me do my job. I could see using a computer for a variety of other tasks, but I really don't like losing eye contact with the players, and a computer screen would be sure to draw my eye away too much.

Heck, I don't even use a GM screen, usually.