I don't think you have to worry about getting the glass scratched - the glass is very tough. I had a screen protector at first but ditched it and haven't seen a single scratch. You're more likely to have to replace your screen if you drop your phone and it shatters.
PLUS, if you get some scratches, you can then get a screen protector at that point (like invisible shield) and it will basically cover up your scratches! I think that is the more practical solution so that you can enjoy your naked phone, but if you are concerned about having it be perfect for reselling or something, I guess that is a different story. Still I think the glass is hard to scratch.