Next, someone is going to write that it was not FDR's programs that saved the day but the command economy of WWII and the subsequent economic hegemony of the U.S., standing alone in an otherwise devastated world.
[WS:] That and also strategic mistakes made by the US labor movement - as described in Fitch's book "Solidarity for Sale." To refresh people's memories - Fitch argued that US model of trade unionism was to embrace capitalism and use it to the advantage of narrowly defined union membership instead of transforming it into a broad mass movement and political force of labor in general. The failure to establish a Labor party akin to those in Europe is probably the key factor explaining the right-wing bend in the US domestic policies.
As to FDR "saving" capitalism - I think it is a hindsight rationalization of the disillusioned radicals. FDR was a reaction to the unraveling of capitalism during the great depression - but a positive one, comparing to that in other countries, especially Italy and Germany. If FDR saved anything, it was the US (and consequently the Western world) from going fascist.
I think it is probable that if the US labor was organized into a major political force as it were in Europe, instead of succumbing to the Gomperist vision of trade unions as wage cartels playing the capitalist markets, the FDR's political legacy would be comparable to that of Lenin and the US today would be another Sweden.
As to your claim that "Eleanor would make a better pick for president" - perhaps, but I do not think it would have made much of a difference. The failure of the US to develop a decent social democracy along European lines is structural not personal i.e. it is a result of the alignment of broader political forces - strong and well organized business enjoying wide public support vs. weak, disorganized and largely unpopular labor. Personalities of leaders would not change that balance of power.
Wojtek