Avoid Eagles.  They are great coins, but you will pay a premium over spot, and when a dealer buys back at most they will give you spot.  You'll lose that premium.

I would stay stick to the trade coins.  K-rands, British Soveriegns, Roosters and the like for gold.

Silver, its hard to beat pre-64 silver coins for the 90% content.  They are also in small denominations if you ever were in a EOTWAWKI situation.  Silver quarters and dimes are cheap - melt value mostly, are easily recognized because a side view of the coin isn't clad and would be in a workable denomination... say a loaf of bread for a silver dime, a chiken for a quarter... you get the idea.

Silver bullion, avoid the Eagles as well... same reason on the premiums.  There are many 1 oz "coins" that aren't legal tender and are known as rounds.  They are marked as being 1 oz 99.99 percent pure silver and have some nice designs on them - so you'll know if they are being shaved for example.  That was a common practice back in the day, and the reason quarters, dollars, half dollars and dimes have ridges on the edge.

Basically, buy it in forms that you can pay spot or close to spot, and avoid huge quntitites like 1 pound silver bars... won't do you much good for trading in an emergency.  I keep small coins and 1 oz and 5 oz silver bars, nothing bigger.