I don't think Senators make it to the Presidency very often (though they often run). Governors are better suited and I have my eye on Mit Romney.
I saw Mitt Romney give testimony in Washington last year, and I was VERY impressed...and you are right, Governors usually are better...
In regards to George Allen, he is a first term Senator, that USED to be the Governor of Virginia, so there is not much baggage in the senate, but he does have the executive experience of a governorsip...Romney/Allen?