Agree on the 24-70 being a better option, used they sell for close to nothing on MPB, compared to buying new. For someone starting with landscapes, it is a very good lense. No need to pay 1k for a tad more versatile 24-120 or even more for the 24-70 2.8. And since you have some longer glass wipdlife already 24-70 shoipd be fine (for me, 70 is too short for landscapes, but a ton of landscape folks are very happy with that length, so it definitely will work).
I sometimes look at the 24-50, simply due to size: as a small, cheap walk around lense that can be used in tight places. But then there is the 40 f2 or 26/28 f2.8, and I have a 24-120 as my primary lense. And a Z30 with the 18-50 for those accasions, if nobody esle is using it.