“A gold coin works for me. What say the rest of you? :)’
Would the price of gold coin be set, say a $20 gold piece, or would you have to work out the exchange rate based on the actual price of gold at the time you used it to buy something?
You're looking at it from the wrong direction.
Gold coins are valued by weight. You don't set the value of a 1/10 oz gold or silver coin in dollars. You set it in the amount of product or service the seller is willing to provide for that 1/10 oz.
I will sell you a cart of groceries for 1/10 oz gold coin. You take it or go to a place that will give you more groceries for your money, or you go to Whole Foods and get less (grin). Does a $100 bill buy the same amount of groceries at Save-A-Lot as it does at Kroger, Winn Dixie, Publix or your local produce stand? No reason a gold or silver coin should be any different.
You earned $100 a year ago. Can you spend that $100 and get the same goods that you could on the day you earned it? There is nothing "fixed" about the value of any medium of exchange.