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I use primes (though not the specific ones you mention), the 24-70, and the 24-105. For the use you describe, and specifically the need for light and versatile gear, I would go with the 24-105.
The stories of 24-105 performance problems are overdone in my view. Yes, the 24-70 can produce "better image quality," but the 24-105 can produce excellent image quality, especially when you correct - if necessary - the barrel distortion at 24mm. Used skillfully, this lens on a full frame body can create photographs that can be printed quite large with excellent quality.
The 24-70 is a bulky and heavy lens. Where weight is concern, on that count alone it would not be my first choice. It also has a much smaller focal length range, and I find that 70-105mm range to be very useful. I've actually used this as my only lens on week-long backcountry pack trips in the Sierra. The IS feature will useful on those occasions when you do need to shoot handheld, and the f/2.8 "advantage" of the 24-70 may largely be negated by IS for the subjects you may be likely to shoot and the fact that you will carry a tripod.
I generally think that limiting yourself to a prime or two for landscape can be a real liability. Yes, you could pick one or two very small primes (like the 40mm pancake, for example), but for most of us the flexibility of the zoom is critical. Even the image quality issue may end up arguing for the zoom. While at 40mm (or whatever your prime is) the IQ might be slightly better (though not likely much at smaller "landscape" apertures), at other focal lengths that might be more ideal for some compositions you will have to crop the prime shot in post, thus losing resolution. On the other hand, the zoom lets you crop in camera with essentially no reduction in IQ.