I alluded to this issue in another blog and though I'd do some quick research and see what I came up with. I confess that wikipedia was my source, but I have some confidence in their timelines if not always in their text... So for your amusement prior presidential experience, going back quite awhile, but not all the way... I counted all state and national legislative and executive experience.. state senator, state rep, governor, lt governor, us rep, us senator, and VP... In order from most to least:
LBJ 2 years as VP, 12 as US Sen, 12 as US Rep...total of 26 years before assuming presidency
Ford 1 year as VP, 14 years as US Rep...total of 15 years before...
Nixon 8 years as VP, 3 as US Sen, 3 as US Rep... total of 14 years
Kennedy 7 years as US Sen, 6 years as US Rep...total of 13 years
Harding 6 years as US Sen, 2 years as Lt Gov, 4 years as a state senator... total of 12 years
GHW Bush 8 years as VP, 4 years as US Rep... total of 12 years (to be fair...tons of other relevant experience....)
Obama 3 years as US Sen, 8 years as state senator... total of 11 years
Truman 4 months as VP, 10 years as US Sen... total of 10 years 4 months
Carter 4 years as Governor, 4 years as state senator.... total of 8 years
Reagan 8 years as governor... total of 8 years
Coolidge 2 years as VP, 2 years as Governor, 3 years as Lt. Governor... total of 7 years
Hoover 7 years as Secretary of Commerce ( does this count...I'll give it to him)
FDR 4 years as Governor, 2 years as state senator... total of 6 years
G W Bush 5 years as Governor... total of 5 years.. do we wanna count owning a MLB team?
Wilson 2 years as Governor... total of 2 years
WILD CARDS: Taft.... tons of semi-relevant experience for example first provincial governor of both the philippines and cuba and lots of other stuff. Eisenhower...no government experience as originally defined but obviously lots of relevant experience.
Further caveats... I'm sure many above had other somewhat relevant experience in their life that should be counted... but I counted state level and federal level legislative and executive experience.
I don't maintain this is a perfect list... but still interesting....