Mercury would be awesome. There's so many possibilities for planets and new species... For more than $10 I'd like to see them tap that potential. Maybe add another peace zone somewhere similar to The Tower. I dunno... Just would like to see more expansion in the first expansion as a good faith move to the people who have been willing to invest the time and money into it. I'll still play the new expansion because I preordered the special edition, but what I've seen has yet to impress me.