Hello, practically speaking, it's up to you to know what focal range you like best.
For landscapes, if you do not need a combat AF, the 5D2 is a very good camera, at a very good price. I shoot 90% of my pictures low ISO on a tripod, and I gave up upgrading to the 5D3, for the simple reason it doesn't bring me enough to justify the switch. The main advantage (in my case) would be the integrated horizon, the 100% viewfinder and the extra build quality, but IQ would not improve (at least with the ISOs (100-400) I am using. Plus for not so fast moving subjects, the AF is decent.
The 24-70mm is a good lens, but way overpriced IMO. Unlike many others, I do not feel the need to have exactly matching focal zoom lenses (14-24, 24-70, 70-200), I use zooms only for what they are: several lenses in one. Primes force you to think a bit more about the framing.
My opinion : buy a 5D2, it's a tried and proven camera, this will increase your IQ from a 7D. You can wait for the 6D, but I doubt the sensor tech will be much better than the 5D2, and it you will likely get a cheaper built than the 5D and 7D.
I would get the 17-40, since it allows you a wider view. With the 24-70, you'll end with a 38mm as your shortest focal on your 7D, for 3 times the price.
I guess you already did the the financial balance :
24-70mm : 2299$, 17-40mm : 729$ + 5D2 :1699$ = 2428$
Add later a 50mm 1.4, and this is all you need. Assuming you keep your 70-200mm of course.
Forget about the slight sharpness differences, this is for pixel counters, have the gear that cover your needs, and use it to make nice pictures.....