I have a 5D (original version) and a 1Dm3, these two cameras are pretty close in IQ. The 5Dm2 would probably be significantly better IQ I presume, but I've never had one. I've heard others say they still liked the old version, though, I would guess this would be more for lower ISO usage though, as the new version certainly must have better high ISO performance by all accounts.
I also have a Tokina 10-17, not sure how much it's like the 11-16, but what I find with this lens is it's very sharp but has a lot of CA. I do wedding photographer mainly, where this isn't such a problem, but for landscapes I would be much more bothered by it.
I guess I would suggest getting the 5Dm2, as it would probably give you the most quality for landscapes in the smallest package. The 1Dm3 is very heavy, wouldn't give you as much focal range for landscapes (the 17-40 would be 22mm on the wide end, although I love using this lens on the 1Dm3). The image quality for landscapes wouldn't be as great an increase from the 30D to the 1Dm3 as it would be to the 5D2 (although the 1Dm3 does give amazing quality for a 10mp file, on a per pixel basis it's one of the best ever).