The casino bit was the best part and I wouldn't change that, but I'd change the whole "Lisa is the president and Bart's a rocker" by inversing it so Lisa is a struggling musican and Bart's a 'Clinton-esque'--yet Republican--scandle ridden president, drop the "Gold" subplot and show Maggie in astranaut training while Homer and Marge tour NASA (Not another Simpson Astronaut!)
Have Milhouse and Nelon be Lisa's roadies and Lisa could be performing in the jazz/blues music fest "Murphapolluza" in tribute to Bleeding Gums Murphy that's about to tour DC and have the conflict be Bart trying to tighten the ban on Illegal drugs in Washington DC and raid the Murphapolluza, putting Lisa against Bart and Forcing Maggie, Marge and Homer to take a trip to DC.
Oh, and NO GODDAMN SILLY SCI-FI GAGS!!!