Thanks! The randomly placed tiles were a quick hack to get something going, and it kind of just got left in there as I concentrated on other things. Yeah, I might look at improving the placement of things. And yes, sometimes you get a fairly clear path to the exit.
The random maze levels - I stole that code from a previous gamejam game I did - its an algorithm dividing the area up into two rectangles, recursing down until a room is in the wanted size range. Then placing doors (spaces in this case) between all rooms that share a wall.