Equally important is finding someone who can step into the president's place should the unexpected happen -- as nine vice presidents have done.
Who fares best among the possible candidates according to these criteria? They may point Romney to a boring, safe choice -- the most notable being Sen. Rob Portman of Ohio, who held two Cabinet posts (U.S. Trade Representative and budget director) under George W. Bush.
Another is Ohio Gov. John Kasich, who spent 18 years in the House of Representatives -- and was chairman of the budget committee when the budget was finally balanced in the 1990s.
What about the gaudier names on the list? Rep. Paul Ryan of Wisconsin is just 42, but seven terms in Congress is adequate training. Florida Sen. Marco Rubio, elected in 2010, has too little time in the capital to be much help with Congress.
Former Florida Gov. Jeb Bush has none. Ditto for New Jersey Gov. Chris Christie, who has spent less time in elective office than Palin had.
If Romney wants someone with sterling credentials who would make a big splash, there is Condoleezza Rice, who was George W. Bush's national security adviser and secretary of state. It would be hard to find a running mate who would create a less traditional look for the GOP -- or one better prepared for the Oval Office.
So Romney can be dull or daring in his decision. It doesn't really matter, as long as he's good.
And if the next vice president doesn't offer much fodder for comics? No problem, Governor. Something tells me they'll find material.