[Callers] challenging contras

Hello, I am posting this on both the sharedweight and trad-dance-callers lists: Next month at the Downeast Festival in Maine I am scheduled to do a short session which I have called "challenging contras." At the time that I suggested it, I thought that I fondly remembered enjoying challenging dance sessions at dance festivals. But as I think more about it I realize that the only ones I can actually remember were sessions where the dances seemed so complex that it was almost impossible to get 4 or 6 people together at once who understood what to do, or on the other hand being somewhat disappointed because the dances didn't seem challenging enough. I am sure the line between too much and too little is probably different for everyone. Can anyone suggest dances that experienced dancers might find somewhat challenging, perhaps something with an unusual figure? I have heard several people on this list mention that anyone can dance anything as long as the teaching is good enough, so that will be my own challenge. I plan to try a couple dances that are not the standard duple formation, but I would like to find at least one that is duple, so any suggestions or advice are welcome. If you can also include the transcription or tell me where to find the dances I would really appreciate it. Thanks in advance! Richard