Thanks Doug Eng for the next couple of drill ideas, featured in his article in the May/June 2013 issue of TennisPro magazine.
Open Season introduces the concept of hitting to the open court. Coach feeds ball. Coach stands in one half of the court, so player must hit to the other half.
Variation: when I tried this with a red ball class recently, I combined it with a bounce feed/serve challenge, so I was not feeding the balls - the students were bounce feeding to the open court.
Harder: Coach may change position/move to other half of court after tossing the feed.
Hardest: Players pair up as tossers/hitters.