I'm always trying to decide what is the right tool for the job. If it's a one-time thing that's just about writing, probably a doc for each group or even the whole class is enough. But if there will be files or media posted, or if there will be multiple projects, then I go back and forth between Sites and Wikispaces.
I did not use Wikispaces at all last year because our school has gone over to Google apps in a major way, so I thought I would be consistent. But W. does have their project feature, after all, and as I have discovered, even a category expressly aimed at the classroom. Here's what got me to experiment again this year, with one of my classes: the "assessment" feature. A graph can show for each student how much she has been engaged on the wiki. I'm not sure if that will save me from tedious searches of students' posts, but I want to find out.
It seems that in Wikispaces I can't give regular pages a hierarchy, though maybe I'm missing something. In Sites when I create a page I can always choose to nest it under a previously created page. Also, when I tried forming teams in the projects section, the editing was acting weird and it was time consuming; I hope that was a fluke.
Today JP groups will start posting research results. The experiment begins.