There's hope! I took the entire skirt off the bodice and separated all the chiffon overlay pieces last night, then repinned the side seams. Lo and behold, this time they matched up! (Note to self: you're experienced in sewing enough to know that a 2.5" differential in seams is typically not a pattern error, but operator error!) The side edges of the front panels are cut on the bias so you really have to play with the shorter edge of the front piece to get it to match the longer side of the back (and the bias cut is critical here, I've now learned).
I'm anxious to stitch it again and see if it's fixed but my sewing machine is acting up. The bobbin holder is bouncing around occasionally and making a clicking sound. Consequently, the stitching isn't even and I think is partially to blame for the bad seams. Now this happened before and I fished out a stray pin but after taking most of the machine apart the other night, I found no pins. What gives? If anyone else has a Singer Quantum Futura and could help troubleshoot, I'm all ears!
P.S. - you've probably noticed a change to the blog design again. I blame it on the CAB dress frustrations. I needed some creative expression to actually work so I took it out on the blog!