My favorite coin is the half dollar. My local bank does not usually have them available that day, but I can order them. The boxes cost $500, but the nice thing is that the dates are much easier to see.

Coins before 1964 are 90% silver and coins from 65-70 are 40% silver. The only problem is that it is harder for my kiddos to buy a share of the action because of the total cost and because all of the gains happens with just 3-4 coins.