Hi miki .
I was experimenting with snub square tiling, to get some irregularity into maps while still having tilling and reusable components. Although the individual shapes don't fit the grid, they do periodically tile into larger areas that do tile onto the grid. And I was working with these larger areas as entities.
Maybe pentagons have such a tiling ? Perhaps Cairo pentagonal tiling? Some pentagons would need to be chopped up. And you would need parts of at least 4 pentagons on each square tile. And rather than one tile you would need a bunch of them to account for the different possibilities. In order to make paths like in your example image.
I agree that the snapping grid is an important tool and it needn't be limited to a square grid. Being able to snap a doorway to a doorway or a flat edge to a flat edge would open up a lot of possibilities.
I've changed my approach to modeling things room by room that can hopefully be stacked to make buildings. It would be good to have more snapping options to stop things being too square.