The optimal solution would be a purpose-built dungeon mapping app (any app developers out there?
![Wink ;)](./images/smilies/icon_e_wink.gif)
I had been using Notability, which has graph paper as one of the options. But it has the glaring omission, IMO, that there's no (useful) way to draw a good circle. I suck at drawing freehand circles. You can draw perfect straight lines but not circles.
Am I the only one trying to do this?