(Photoshop courtesy of Outside the Beltway)
Putting him on the $10 makes sense (cents?) since most people have no idea who Hamilton was or why he was put on our currency in the first place (he was instrumental in setting up our modern banking system and was the first Secretary of Treasury). Personally, I think he was one of the more interesting Founding Fathers who lived a charmed life until he caught that bullet from Burr. But he was never a President. Calls for replacing Jackson on the $20 or Grant on the $50 miss the point that, no matter what people think about them today, they were Presidents of this great land while Hamilton was not (Franklin on the $100 was also not a president, but everyone would agree he was a greater Founding Father than Hamilton was).
Perhaps a better proposal would be to put Reagan on the $1 coin which has had the most turnover in portraits in the last 50 years having everyone from Anthony to Eisenhower. And to mollify the anti-Reagan crowd (of which there are many), it could be a commemorative issue, similar to what we do with State quarters today.