A friend of mine asked me to make the costume for her. It was a last minute thing and we didn't have any time to ensure a good fit. The shoulders ended up being too wide for my liking, and the torso too long, but considering the rush, I was pretty happy with the fit, and so was she (and she was the one who had to wear it, so that's what matters).
The pattern I picked Simplicity 2325 (view B). I went with cotton for cost reasons and because it was supposed to be worn to an outdoor event in August. While it looks like I changed the pattern a lot, most of it is pretty superficial. IIRC, the bodice has separate pieces for the pinafore and the dress, so I simply omitted the pinafore pieces. The skirt is actually all pinafore, so I just made that in the dress fabric, leaving the ruffle off.
The collar and sleeve scalloped edges probably caused the most problem because I had trouble getting them to lay flat. I made several patterns and muslins before I got one that worked.
This pattern took more time than you would think that it would. Due to the bulk of the skirt and the gathering involved, sewing it to the bodice was cumbersome and time-consuming. It wasn't hard, per se, but I certainly wouldn't recommend this pattern if you want something you can knock off in an afternoon. The difficulty her would probably be for an advanced beginner.
The contest rules go up tomorrow and the contest starts October 24. I hope you'll be participating!