What you always want is multiple layers of protection. Depending on just one layer - no matter how good - won't work for the long term or under really severe conditions.
As an example, in a gun safe, put a coat of some good corrosion inhibitor like CorrosionX, Eezox, RIG, Boeshield, Sheath, whatever. Even a good CLP is good enough - because it isn't the only protection. You may want to use a dry corrosion inhibitor in some circumstances. Layer 2 could be a VCI bag, like these:
http://www.polygunbag.com/gunbags.html, and layer three could be having a Golden Rod in the safe. Instead of the VCI bag, you could get gun-wrap paper. I also use the Bore-Stores storage bags, which are impregnated with silicon and also protect against the guns knocking into each other or falling because of their thickness.
For smaller items like magazines, tools or reloading dies, the first 2 layers would be the same, but then put the items in a sealed plastic box of some type (which protects from outside moisture coming in, and concentrates the VCI material in a small space) and toss in some dessicants or some VCI tabs (available at Brownell's) before closing the top.
Using multiple layers like this will give you YEARS of protection.