Heya,
I wouldn't trade up for the 14L. It's a good lens, mind you, but it's not a great lens. Compare the 14L to something like Rokinon/Samyang 14 F2.8, and see if you really think the mark up for the L seals it for you. For me, I would not bother with that.
That said, if your thing is primarily landscape, and you're ok with spending serious money, consider a few other lenses instead (this is the year of the ultrawide it seems!):
Canon EF 16-35 F4L IS
Canon EF 11-24 F4L
Tamron 15-30 F2.8 VC
Realistically the 16-35 F4L IS, for the money, is the best performer. If you truly need wider, the 11-24 is peerless for full frame 11mm that is not fisheye. If you need faster, Tamron's latest offering pretty much takes it with it's range of 15-30, F2.8 and VC. Each has a place. Just depends on you.
For me, landscape lenses require three things: 1) flare resistance, 2) sharpness in corners stopped down, 3) ability to take standard filter systems. So for me, of all these lenses, the 16-35 F4L IS is the one that I would go for, it has the performance for cost, and nails all the three criteria I would hold as most important for a landscape lens.
Very best,