You could start with an empty array and as you determine that tiles are potentially okay for your spot, append them to the array. Then choose a random item out of the array. Then clear the array and start with it empty as you check the next spot.
You could start with an empty array and as you determine that tiles are potentially okay for your spot, append them to the array. Then choose a random item out of the array. Then clear the array and start with it empty as you check the next spot.