CDs dont play the market, once your locked in, your locked. MMA and IRAs do mess with the market.
No way I would deal with a rental, if you get some shitbag in there, there goes all your investments, plus how much time would have to devote to it.
Gold/SIlver is always a good bet, just have to ride it out, its no different than the stock market honestly.
Land is good, but do your research, ALOT of research, check the area within 20 miles in every direction, look at what might be potentially built, look for places that you get the Mineral and Timber rights, it could be possible to make money off of the land you buy, etc etc. Check Lands and Farm. com for land. OR even just drive around an area you like and maybe work towards a nice Bug Out Location.
Ammo, food, water, guns, gun parts, etc etc would always be number one to get IMO.