If you are going all the way in there to climb Inspiration, do the East Ridge for sure. There's a handcrack on it that is worth the whole approach. And the summit ridge traverse from the East summit to the West summit is one of the most photogenic areas in the Cascades.
As for the descent, we did 2 or 3 double rope raps off the summit, down the West Ridge. Then at the point where the W ridge just flattens out a bit, we started rappelling down the South face. It is pretty vertical and we figured there would be less of a chance of getting ropes stuck. (Plus only one of us carried boots, so the other 3 would have had to downclimb that snow gully in rock shoes). There were no other rap stations anywhere on this part of the south face, but the rappels went fairly well even though we had to leave tons of stoppers and slings. I haven't done the regular descent off the W ridge so I can't compare the two decents, but now that there's rap anchors built on that part of the S face, it might be worth considering.
If you want beta on the climb let me know.
my 2 cents . . .