I am biased, but if I had the money for a long term investment I would look at leveraging it in Real estate rentals. Low interest rates, easy positive returns, and some possible tax benefits. I have seen estimates of a 5 year return to post recession prices. If so, a smart investor would leverage at 80% with a 6% to 6.5% interest rate. Right now you can buy a good rental for around $160,000 that will return about $1200 a month. Minus taxes and insurance and management fees you should get about $850 a month. That's $10,200 a year. Interest on the loan of $128,000 should be around $8320.00. That leaves $1880 a year for vacancies and repairs and to pay down the principal. If prices go up 50% over the next 10 years that would be a $80,000.00 equity gain. Take out 10% for resale costs and that leaves $54,000. Thats a 150% return on the original investment of $36,000 over 10 years. Not great but decent. That is if the rent doesn't go up and the prices stay at the minimal end of expectations. Add in any tax benefits and the return will be higher.
The numbers I listed are fairly loose and do not factor in any major repairs or long term vacancies. At the same time, however, if an investor has cash he can buy cheaper with better returns.
Every time I hear about silver or gold, I think about the prices of silver at 1980 compared to most of the 1990's and 2000's. For the most part, it has been a bad investment long term.