PVC works fine, consider a rack (shelf) out of PVC, drill a bunch of holes in it, then attach it to your return line. Instant flow throughout the aquascape.
Are you putting in a DSB? If so, you could have the rock elevated above the sand. This allows flow under the rock and keeps detritus from building up and helps prevent the possible calcification of the sand under the rock. However, if you only elevate the rock and point high flow returns at it you will get sand storms. A pvc rack with holes gives the best of both worlds.
Since you are going room divider ,make the rack narrow and long, about 4-5" tall. Add sand, then stack the larger pieces on the bottom of the rack and build up from there. Some folks actually drill holes in the rock and plastic tie it to the rack. I've seen some with multiple level shelfs that look pretty good.
Personally I put the large rock on the bottom of the rack and epoxy the smaller pieces as I build up the aquascape. Not all the rocks, just the structural strategic ones.
There is a thread here about an acrylic shelf and it also looks real good.
I'll post some pictures of mine along with that roll out light fixture tonight.