Hi Chris, for years, I have been v. afraid of heights (still am - Empire State building - oh no!), and I had fear of cable cars when I took the Eastern France tour years ago. It includes Chamonix. I wanted to take the cable up, but only made it to the half-way stop. Then, I took the My Way Alpine tour about 5 years ago. In Bolzano, I trembled as I took a very small cable car up to Oberbozen. While doing so, it occurred to me that the other folks in the car were commuters. Huh. When we got to the Zugspitze later in the tour, I made myself go and jammed myself in the middle of the large crowded car. Couldn't see much, but ok. Coming down, I wanted to see, so I positioned myself for a better view. Tense, but not as bad as I thought. By the time we hit Lauterbrunnen, I figured out there were a bunch of sights I would miss out on if I avoided funiculars and cable cars. So I gamely held my breath and went. And very happy I did since I love Mürren and had to take some type of cable to get there. Finally, we made it to Chamonix. I decided to take the cable to Aiguille du midi to the top. I faced the mountain, not the rear of the car facing the receding ground, but the front. There was a small open window. It was so beautiful and thrilling, I took little videos going up and then back down.
I am still not a fan of heights and hate the escalators in the London tube and in Washington DC. But somehow, maybe because it was so necessary to get where I wanted to be, I found ways to distract myself when fear and/or panic set in: looking at people's hats, noticing someone had a dog, noticing baby carriages. I was amazed, still am, but it became less difficult to do. I still could not make myself take that little 4-seater between the mountains, but I am glad I am less fearful.
Now open ski-lifts - that still remains a no-no. Compared to them, large cable cars are a breeze. Maybe think it over and go half way up? There is a nice cafe and picnic tables and lots to see, maybe more relaxing than all the way at the top.
Best, Debbie