I dont think you can use speakership as a springboard to run for president and I doubt you will find many in history. Being in public eye over partisan battles you wage in congress against the President ruins whatever "i will bring this country together" qualities.
Usually being Speaker means you give up the hope to ever be president, I don't think Ryan's situation is any different.
Henry Clay, John Bell, James K. Polk, and James G. Blaine are the only Speakers to become a major party's nominee. Polk became President.
James Nance Garner was Speaker and FDR's first VP. (He then ran against FDR, who dumped him in response, for the third term.)
There's only four living former Speakers, same number as Presidents. Newt, Hastert, Pelosi and Boehner.
LBJ and Bob Dole are the only Senate Majority or Minority Leaders to ever become their party's nominee, and only Dole was it at the time. Though Charles Curtis and Alben Barkley became VP.
James Garfield is the only sitting Representative to ever be elected President.
Benjamin Harrison, Warren G. Harding, John F. Kennedy and Barack Obama are the only sitting Senators to ever be elected President. (Andrew Jackson's last elected office had been Senator but he had been gone from it for three years when elected President.)
The best single chance of becoming President actually probably is being VP. Even though only four have ever been elected to the Presidency (and two of those are John Adams and Thomas Jefferson and shouldn't count), nine have gotten to it by way of the President dying or resigning.
