Here are a couple elements I like discovering.
1. “Easter Egg” straights. Where you can make a short sequence of corners into a mini-straight if you get the line just right. See Station #5 at candlestick http://www.ggcbmwcca.org/media/kunena/attachments/47/20120729-candlestickSiteMap-FINAL.pdf
2. “Dummy” corner cones. Where the cones marking a corner have nothing to do with the line you take to set up for the following corner. e.g. if you hug the inside line of the corner then you are going to exit at the wrong speed or angle.
3. Like Hal, I like the challenge of high speed straights followed by heavy, tight braking which then leads to a medium speed something or the other. This punishes you if you overbrake or underbrake.