My 2c:
For E powered rockets, you may get by with Estes materials. I have several thin tube/balsa fin birds that do just fine on E15s and E30's.'s with no mods.
However, I generally use epoxy for MPR, but as long as you have wood/cardboard bonds you can use yellow glue if you build properly.
Like someone later said, you usually get plywood in MPR kits. For scratch builts I generally would recommend plywood also, but I have even used reinforced foam board. G10 isn't bad either, but you will need Epoxy in this case.
You don't need fiberglass on mid-power. I have to think, but I don't think I've fiberglassed any of my mid power rockets. On my Big Brute, with its surface mounted fins, I wish I had.
The theme here is that the answer to the materials question depends a lot on the building techniques and the application. Thrust to weight plays a big part, which is what Ken was getting at in his example. You also have to remember that more rockets break on landing than during boost.
BTW, I know of one M/N powered rocket that used no epoxy or fiberglass, and another that was built entirely with Liquid Nails...what will work just d'pends....
STILL, if you are unsure, epoxy and thru the wall plywood is the best bet.