I have both the 7D and 5DII, both are capable, but the lower noise properties of the 5DII and full frame sensor are it's big advantage for night landscape work. Whether the rumoured 5DIII will be a step forward or backwards is yet to be seen but I'm sure that the 5DII will still have a good resale once the new model appears.
H makes a good point re sensors, I've owned the 20D and 50D and shot comparisons of the same scene, the difference was almost negligible and when I look back at some of the images taken with the 20D I'm not convinced that higher Mp count is better.
I'm not that impressed with Canons ultra-wide zoom lenses, my 16-35 is quite soft at the edges even stopped down (a fairly common complaint with that lens), the Nikon 14-24 F2.8 is reviewed as being far superior (i.e. sharper even than Canon's 14mm prime) and will work on the 5DII with an adapter. IIS Member luigi (Luis Argerich) has done some nice work with the 5DII /Nikon 14-24 combo. I seem to remember Fred (Bassnut) doing some very
nice time lapses with a 5DII and 24mm F1.4 prime.
Buy the 5DII, you won't regret it.