1. People sometimes think it’s best to use spray foam and exterior foam to insulate really well. I think there are some cases where that is true, but not necessarily. It’s not only that it is more expensive, but also in many cases I don’t think it is good building science/physics/durability. Hence, not green. (link to old post) Generally I think cellulose is the way to go.
2. Sometimes it seems like using particleboard vs plywood is better or TJIs (wood i-joists) vs dimensional lumber (2x8s, 2x10s) are better. Smaller trees but more glue. But here’s a great article about that too. Again, local economy, susceptibility to mold, plus building practices don’t make it a no-brainer.
The basic advice I have is… when in doubt, go for local and the more labor intensive option. Better to put people to work than spend $$ on more expensive products. And when still in doubt, ask your Q at the Q&A section at greenbuildingadvisor.com. Great info and great out-of-the-box green thinking happening over there!