5D replacement

I plan to retire my good old loyal 5D. I need a FF for interiors and architectural shots.
Is it worth the extra $$$ for a 1Ds III or better get a 5D MarkII and save the difference?
Lens that I normally use for this project is 24mm T/S.

Why are you retiring your 5D?

Is it because of wear and tear only? Then the newer 5D II should be the right choice. It is 5D with improvements in some important areas. For your interiors and architectural applications you shouldn't need the AF performance (especially with a TS-E lens, AF is moot), ruggedness or weather sealing of the 1D series. I'd save the $$$ and go with 5D II.

But if you are moving on because 5D lacks in certain areas, then you'd need to see which one of 5D II or 1D III can address the shortcomings.