EC3 can be helpful for that too - if you simply select a category and click search you will see the range of impacts for that category in general across all regions, no need to dive into individual EPDs or regions.
You can also check out the Carbon Smart Materials Palette for a basic discussion of various materials or the ICE Database for a free generic resource of carbon values. This materials pyramid mentioned on another thread about material selection is also helpful, just note that it can be misleading to compare all materials on a mass basis - they all have different densities and functional units on a real project.