yes from the little bit of reading i've done since getting it, it seems that concept 2 is the rolls royce of the rowing machine world. Didn't quite have concept 2-shaped-cash though unfortunately!
Just noticed how old the post is but maybe this will help somebody else using a rowing machine...
Have a look on the concept2 website - it generates specific workout plans based on your level of fitness, how often you want to exercise, how long you want the program to last and why you want to exercise - its pretty good and also tells you the SR you should be working at (you will need a heart rate monitor though, as the intensity of the sessions are geared to HR zones).
I have a Waterrower at home but I have been using the workout schedule from the concept2 site - I tried a C2 in the gym a few weeks back and there was little difference in my performance once I had worked out how to change the intensity, so the program should work for any machine.
BTW, that SR is pretty high! For long sessions try and get your SR down to 20 but increase the intensity and watch your form - I was like a bull in a china shop when I first had the machine but I go a lot further and a lot faster now I have teh intensity/power under control
If you fancy HIIT as Cord suggests, try a straight Tabata Protocol - 5 mins warm up, the 8 x 20 second sets at full tilt with 7 x 10 second rests (well, slow down to gasp for air) then 5 mins warm down - I nearly threw up the first few times but it gets easier! Found a neat little iPhone app to time the intervals, as after about 5 mins of Tabata it gets hard to focus on much!