Because I am obsessive-compulsive I've spent some time researching the origin of our currency system. Coins and Bills are handled by two separate gov't agencies, (Coins = the US Mint, Bills = Bureau of Engraving & Printing) and coins have a much less consistant history than the bills.
In 1928 the bills were assigned their current assortment of Dead Presidents/historical figures. In addition to those we're familiar with, four larger denominations were created at that time, discontinued in 1945 and taken out of circulation in 1969 because they were so seldom used. They are:
$500 = William McKinley
$1000 = Grover Cleveland
$5000 = James Madison
$10000 = Salmon P Chase (Chase was an abolitionist who served in several gov't positions, but in particular as Sec of the Treasury in the 1860s.)
Coins were minted with symbolic and historical imagery until 1909 when the Lincoln penny was introduced. Over the next several decades each coin rec'd a Presidential figurehead -- the Washington Quarter in 1932, the Jefferson Nickel in 1938, the F. Roosevelt Dime in 1946, the Kennedy Half Dollar in 1964 and the Eisenhower Dollar in 1971. In 1979 the Ike Dollar was replaced with the Susan B Anthony Dollar, which flopped. However more WERE produced in 1999. In 2000, the Sacagawea Golden Dollar was introduced, but it was apparently a limited run.
Using the Inflation Calculator,
http://www.westegg.com/inflation/ I determined that the value of US currency in 1928 was (conveniently) about 10 times what it is today. So from the perspective of a 1928 American a penny was equivalent to our 10-cents, a dollar = our $10 etc...
That bodes ill for our modern penny, which now represents a value so low that Americans in 1928 didn't even bother measuring it.
Interestingly the value of currency was about five times what it is today in 1969, when the gov't took the insanely high bills out of circulation. At that point the highest USEFUL bill was the hundy, which was worth to them about what FIVE-hundy is worth to us. So (thanks to inflation) the $500 dollar bill seems poised for a comeback.
Since the Bureau of Engraving & Printing wants to hand off production of the Dollar to the US Mint, and the $2 bill has never really taken off, it would make sense for the long haul to discontinue those bills. The $2 value could be resurrected as a coin, although who knows if it will be any more successful in that form. That leaves a nice progression of six bills, as follows: $5, $10, $20, $50, $100 and $500.
The current figureheads on these bills are:
$5 = Lincoln
$10 = Hamilton
$20 = Jackson
$50 = Grant
$100 = Franklin
$500 = McKinley
Pennys are pretty much obsolete these days. Eventually they'll be discontinued too. But for the time being we could have seven coins: 1c, 5c, 10c, 25c, 50c, $1 and $2.
The current figureheads on these denominations are:
1c = Lincoln
5c = Jefferson
10c = F Roosevelt
25c = Washington
50c = Kennedy
$1 = Washington/Sacagawea
$2 = Jefferson
That adds up to thirteen different denominations, one for each of the original thirteen states. Or, by discontinuing the penny, a nice round number twelve. Or by paring it down to only the most currently useful denominations (1c, 5c, 10c, 25c and $1) a weird eleven. Or by dropping the penny and rounding everything to 5c, a pleasant ten.
Most of the figureheads on currency are Dead Presidents, with Hamilton, Franklin and Sacagawea the exceptions. Most of these people are held in high esteem, although in retrospect Grant is thought to have been a poor President. (He IS credited with turning the tide against the Confederates in the Civil War.)
The most recent well-circulated survey of Presidents was conducted in 2000, by the Wall Street Journal and the Federalist Society. Here's a link to it:
http://ragz-international.com/pres.pdf
According to their experts, the top ten Presidents were:
1. Washington*
2. Lincoln
3. F Roosevelt
4. Jefferson
5. T Roosevelt
6. Jackson*
7. Truman
8. Reagan
9. Eisenhower*
10. Polk
The * indicates that they were also war heroes. T Roosevelt's service in the Spanish-American War is highly regarded, but it was relatively insignificant compared to his political career. The War of 1812 was fairly inconclusive, but Jackson is credited with salvaging America's prestiege by winning the Battle of New Orleans (after the war was over...)
The next batch of Presidents that were highly regarded by the survey participants were:
11. Wilson
12. Cleveland
13. J Adams
14. McKinley
15. Madison
16. Monroe
17. L Johnson
18. Kennedy
All are considered to be above average.
Both Benjamin Franklin and Alexander Hamilton are also highly esteemed, but Hamilton is vulnerable to replacement. Pro-Reagan-on-the-currency advocates are pushing to have him pushed off the ten. Alternately, they'd like to get Reagan on the dime, sharing it with FDR.
In my opinion, FDR belongs on the dime. Benjamin Franklin probably deserves his place on our currency too. That leaves five slots for Presidents on our bills, which if synched with the WSJ/FS survey should probably go to Washington, Lincoln, Jefferson, T Roosevelt and Jackson.
How about this reconfiguration, which makes as few changes as possible?
$500 = Jefferson (sort of shoved to the extreme of the spectrum by default, but in the long run this will be a fairly common yet prestigious bill.)
$100 = Franklin
$50 = T Roosevelt (replaces Republican Grant, this denomination will eventually supplant the $20 as the most common bill -- deserving of a bipartisanly respected Prez.)
$20 = Jackson
$10 = Washington (#1 x 10, to honor his first prez status.)
$5 = Lincoln
And for the coins:
$1 = Truman ("the buck stops here...")
25c = Reagan (or Eisenhower)
10c = F Roosevelt (March of Dimes)
5c = Eisenhower (or Reagan)
These three units, being relatively untested or potentially obsolete, should get the slightly less esteemed guys:
$2 = Polk
50c = Wilson
1c = Cleveland