If anyone is looking for a new workout to try, I'd definitely suggest rowing. Your gym probably has a rowing machine (an erg), and if anyone's interested I could give you some workout suggestions and tips for how to get started.
Rowing is a very healthy workout option, and it doesn't take long for you to get a great workout in. It's also both strength- AND cardio-based. I'm pretty sure it's integrated into CrossFit on some level (or, at least, it was a couple years ago) as well.
I used to row in college (eights, fours, scull) and agree with you that rowing is wonderful exercise, both aerobic and strength. The dumbest thing I ever did was sell my scull before leaving NJ for San Diego. There's a reason why Olympic rowers train down here.
Modern rowing machines replicate the feel of rowing on the water very well indeed. If you close your eyes you almost feel you're on the river again ....