Do you mean in terms of ideology/political style, or in terms of their performance in the primaries?
Comparing Lamar Alexander to Rick Perry is just plain disrespectful to Lamar.
The closest parallel I can see is Forbes-Cain in that both are the "rich businessman with no elected office experience and a highly regressive tax reform plan."
Santorum has the views of Gary Bauer but has run a campaign that is similar to McCains, while Romney has been this years Bush, as he has been favored from the start.
Lamar is much more moderate than Perry. He was basically a reform-minded center-right governor in the '80s and still gives off that vibe in the Senate. Rick Perry wants to get rid of the Department of Education; Lamar Alexander used to run the Department of Education. In terms of campaign style, Lamar's problem was that he tried way too hard to be the down-to-earth nice guy and came across as sappy (the plaid checkered shirts, the "Come on along" slogan); Perry had the look and the image down, but when he opened his mouth he had nothing substantive to say.
I'd recommend reading
Losers by Michael Lewis. It's about the 1996 Republican primary. You will come away realizing how much of a shill Phil Gramm is, how weird Steve Forbes is, how fatally genuine Morry Taylor was, and gain a tremendous amount of respect for John McCain.
