I think folks will wanna pick and chose all together. It's hard as many will eye certain pieces, and some will no longer be friends afterward
Fights may ensue.
But honestly, you need to put the batches into the best groups for the sizes you have for the tanks.
A saw to quickly zip off pieces to the right size will help.
Slate bottoms(they sell tiles of slate 25cm squre or 30cm sq etc), can be used and ceramic drill bit is the best for making holes for screws if you want to make a rossette root pinwheel effect that will not move.
You can cut the pieces at angles to get all sorts of effects.
I'll find some hollowed logs or pieces with nooks and crannies for plecos and other fish concerns.
So I'd suggest you all get together once the wood comes in, then make groups of the wood and a few spare bits based on everyone's opinion in the group, then divy it up based on who has what as far as the tank.
The goal is to get the best match for the tank size.
You can trim the wood down from there.
The sizes you folks are after are easy to find.
The larger cool one are tougher, but even for a 120 Cm tank, no issue.
I'll be after character more than anything.
A wire brush and a 30-50 Gallon trash can to soak will be useful. Soak first for 1-2 days, then take out and let dry a bit(1-2 hours), then brush off the grey, lichen etc, any dirt, spray down good, then soak some more. Repeat maybe 1-2x. Get the wood clean. Any really soft or whitish air wood/dry rot, cut out with a knife.
It has no bad "bacteria or parasites".
You can easily drill into it also to make caves, or holes for fish, plecos, etc, do this only where aesthetically pleasing and refrain otherwise, or place holes over of site from main view.
Wood is a really nice medium to work with, much easier to modify than rock and lots lighter, easier to get a 3D shape to your layout.
Rock is good for placement of wood, stabilizing it etc, and for open layouts for those damn fish that always hide.
Regards,
Tom Barr