Long teles are also good at picking out details in what are sometimes bland landscapes otherwise. When you have strong lines, particularly in low contrast scenes, such as mist, teles can be ideal. Like you, it's something I want to do more of. I have a habit of travelling a bit lighter when I am out for landscapes, so often leave my 300 f/2.8 behind, but I have taken a few with the 300+1.4x and got a drop in polariser for the purpose.