My initial thought was to just program workouts using free trainer day and using erg mode. I figured I'd just watch TV shows while doing SST.
Being able to do intervals etc on zwift sounds like it could be cool, but with limited time it's like... Wouldn't it be more fun to just watch TV instead?
I really liked the idea of trainerroad as well, though I figured I could have that going on a small screen while watching TV.