Quote from rwk:
Gold coins can be a good investment, because they are durable (can withstand fire, water, or trauma), are pleasing to caress, and can be used to fund getting out of town in a hurry. But all forms of gold have a markup, so probably the best form for investment is semi-numismatic gold coins. The biggest disadvantage is that it takes a little expertise to buy them efficiently.

The biggest problem with gold bars has already been stated -- they could be gold plated. You can "help" protect yourself by buying from a reputable dealer, but you might have trouble selling them, especially in an emergency (i.e. the apocalypse). To sell them, you may have to have them assayed, which takes time and costs money.Quote from 1penguin:
What about bars? Are they better or worse than coins? I think the markup should be less, so probably more convenient. Or am I wrong?