Verdict not totally unpleasant. It was also unsuccessful in the sense that I didn't get the titre de séjour or residency permit filed. On the other hand, I didn't expect to get it filed, and I got closer than I thought, so it was definitely a positive experience in that sense.
Got there around 8 am (they open at 9 am for my type of document.) Found and stood in the right line, got told it was the wrong line ("No. No. Carte de séjour over there.") Moved to the "right" line. Got to the front, got told to go back to the old line ("No. Visa Scientifique over there."). Line was now much much longer. Woman behind me eventually verified that I was indeed likely in the right line.
When the line began to move, an obnoxious student pushed in front of me. Got my number (6 people in line ahead of my for my visa type), and sat down. Waited. And waited. Consoled myself with the fact that only 2 women appeared to be servicing the same kind of visa/titre de séjour that I needed and if they were taking their time with other people, they must be reasonable people who weren't looking for excuses to send us all away. Eventually got my turn and a quite nice woman looked at my documents. My marriage license needs to be translated (too long and complicated) and I can't come back until the first date on my rental agreement (makes good sense, plus I don't even know if I'll have the translation by then!). She looked at all my documents and put them in order for me and got me a list of translators (the link on the Prefecture's site is broken, which is really the most important reason I was there today). Very helpful. And now I know which line to start on -- and stay -- in when I return.
There is a moment in J.M. Barrie's Peter Pan where Peter Pan does something of which he is unreasonably proud -- I don't remember what the minimal accomplishment is -- and he crows. I felt like that when I left the Prefecture. I found the right place, I stuck with it even knowing it wouldn't be successful, I got a list of translators, and I found the right bus to make it to the Mairie to register my kids for school.
Then I got to the Mairie to see the sign: Fermeture Exceptionelle: 24 Juillet. And here I was hoping my good luck was going to continue! Still, a productive day.