I bought the 18x18 3 story and was doing each floor artisticly with no interrior walls to have nice designs kind of like a floor garden instead of a rock garden.
Well I've notices some interesting things:
1) Some of the tile sets dont have a full spectrum of options needed to do nice designs. If you have corner pieces of a specific set and you call them NW, SW, NE, SE. Some sets have NW,NW,SE,SW or NW,SW,NE,NE or whatever. So you cant do a nice four corner array like a ridge around the outside or a cute 2 by 2 square in the middle.
1.2) Same thing in a different way with some of the 'artifacts' of the floor tiles like if you have N,S,E,W thin and thick borders for a set you might be missing one of the borders and have two of something else.
2) Some of the tile sets of repeats of the exact same tiles. Now I know some of them are slight variations which might be hard to see to the naked eye especially with the window being so small on a high res screen (I'm 1600x1200 desktop) but once I realized that might be going on I started looking carefully and did find one or two. This may be tied into the repeat problem above where the person in charge might have accidentally put in two of something instead of one of each of something else.
3) **MOST ANNOYING** One particular tile set that made my third floor look awesome to me actually was an halucination! lol! I was able to tile the floor with the tiles but when you walked on them you fell through to the floor below. Kind of funny in a sense. Part of this bug also is the fact that to the other player when you fell through the floor it didnt look like you fell through so it looked like you were walking on the same floor as where you started. My friend was doing laps up the steps, to the middle of the room, to the north west corner and back up the steps over and over again on the same floor as me and I was trying to figure out what the heck he was talking about being wierd until I walked where he did and fell through and followed the same path he did back up to where I started. It looked to me like he was coming up the steps walking to the middle of the room walking on the same level to the north west corner then falling down the steps at the low end and walking to the high end and repeating.
This particular tile set is the really dark grey stones with what kind of look like thick arrows for the four corners. The four corners are by themselves on a page if I recall and then the dark stone is elsewhere. (Might be on the same page, if I get a chance I'll look for it and take a screen shot) Sad because I really liked my design I made with them.
We did joke about putting a vendor in the middle of the 'pit' and marking it millions of free gold and watching people try to walk to it and fall through.
but i dont know if that will ever be real hehe.