The reason for the preponderance of governers (and one general and one cabinet secretary), as opposed to Senators is simple: the Presidency is an executive job, one that requires both leadership skills and an ability to negotiate with one's political opponents to get things done. Being a governor is like a beta test for the Presidency, whereas being a Senator is...what?
This is why Condi Rice won't be successful running for President, not unless she becomes a cabinet secretary (State, please, Mr. President). Giving a bunch of speeches and dealing with the sharks in the press and media would also help.
Anyone who wants to be President must first have been either
(1) in a major political office before, or
(2) WON A WAR, or had a major consequence militarily or through other leadership.
dont pass that test, you will not be chosen President.
Condi Rice does NOT pass the test.
Powell passes, barely.
wes clark... oh yeah, "he won a war" - Kosovo. no wonder he got beat by a guy with 4 months in 'nam.
A place to hone speaking skills and rhetorical devices. I agree with your premise, PLUS governors don't have to vote on bills and have a long "record" of pro-this and con-that. There may be occasional controversial gubernatorial vetoes, but governors are much more "pro" for the agenda items that they send to their Legislatures.