Singin In The Rain (or any other classic musical)
I wasn't sure how i felt at first about seeing good, classic films riffed, but now they're some of my favorites (esp Wizard of Oz). I'd love to see you riff some more because:
The stories tend to be very chirpy and wholesome, which comes off a bit silly these days.
There's often a lot of crazy choreography that would make great riff material.
They're just fun movies in general, and I think having them riffed would be a good way to introduce them to the youths.
Some movies that would be great to riff: Singin in the Rain, Kiss Me Kate, Summer Stock, Harvey Girls