I'd say a higher denomination is appropiate, like $50 or $100. I always thought Teddy Roosevelt and Ronald Reagan should grace those two bills.
U.S. Grant was a great general but a terrible President, I don't know why he got on the $50. And Benjamin Franklin was much better suited the 50 cent piece, but unfortunately they tossed him and put JFK on. Andy Jackson was one of the few decent Democrats we had as president. Keep 'em on the $20. Alexander Hamilton was very much in sych with Reagan's policies, I don't think he should be on the $10 but I'd like to see him on some other currency. And I'm all for throwing FDR off the dime, but I think non-Presidentials greats should grace coinage. Besides, nobody can tell who it is in on those tiny coins. Here's my suggested change:
$10,000 - Wilson (nobody see it or use it! heh heh)
$5,000 - FDR (nobody see it or use it! heh heh)
$1,000 - Cleveland
$500 - McKinley
$100 - Reagan
$50 - Teddy Roosevelt
$20 - Jackson
$10 - Truman
$5 - Lincoln
$2 - Jefferson
$1 - Washington
Wilson is on the $100,000 bill. I think one option would be to bring back the $500 bill to circulation and put Reagan on that. Even though it wouldn't be used much, it would be the most valuable piece of currency in circulation.