Rappel the Solar Slab route with double ropes. Four raps will get you back to the top of the first tier. Then rap Solar Slab Gully with a single rope (just down and to your left). The descent at this point goes a lot faster if you just keep pushing the spare single rope ahead. We always down climb the first short rappel into the top of the gully. Makes about six single rope rappels down the gully. The first two are quite short and the last four are full length. You could combine the last two with a double rope rap, but the 3rd and 4th rappel are best done on a single line or you will more than likely get your ropes entangled. It is an easy walk back to the base of any of the lower routes, so you can leave your approach shoes at the base of whichever route you used to access the 2nd tier slab.
Beulah's Book-Sunflower, 5.9, 8 Pitches, Solar Slab Area, Oak Creek Canyon, Red Rocks, March, 2008