For about $2 more than the cost of a gun sock, you can have a gun case that you can also use to take the gun to the range, stow it in your trunk, etc. Gun socks would protect the guns and take up less room in the safe, but then I'd need a closet to store all the gun cases. Go with whatever path works for you.
I use my guns, so they get carried to the range, cleaned and oiled fairly regularly. Mine is a teaching collection, so I need enough cases to take the whole pile to the range. Guys who only take a few of their guns to the range might be better served with gun socks and a few cases.
For long term storage and rust prevention, see the video here:
http://www.brownells.com/gunsmith-t...iple-tough-premium-storage-bags-prod1154.aspx.
I'd do that if I had a gun I didn't plan to shoot, clean, and oil regularly.
Warning: Midway says that long-term storage in a case can lead to corrosion and damage the gun's finish. I imagine that happens when high humidity and temperature fluctuations lead to condensation. My guns are in a climate controlled space, and they're regularly cleaned and oiled, so I think I'm OK in this regard. But when Larry Potterfield says to watch out, I listen. YMMV.