Based on pure assumption I would believe that the IIn is more expensive while the 1DII and 1Ds are more or less on the same price level.
It's hard to recommend one over the other, but as you can see, one camera has incredible speed and the other has incredible resolution. Pick the camera based on the type of photography you do. If you're into sports and need high FPS, better high ISO performance, fast write times and faster AF, go with the 1DII. For studio portraiture, landscape and macro work, I think you'd be hard-pressed to find a contender for the 1Ds at this price level.
If you wish to see what difference in IQ exists between the 1DII and the 1Ds, just check out the comparison images in DPReview's review of the 1DII. Besides the obvious difference in resolution (ie. one camera being 8MP and the other being 11MP), take note of the difference in the clarity of details between these two cameras.
Both of them are incredible work horses. For most casual shooters, they're overwhelmingly capable. Often I tell myself that I could make do with the 400D, which is plastic-fantastic at its price and size, but human greed always takes over from there.