Having trouble finding the right size pan for caramel

You're right betteirene - the skillet does move things along more quickly. More surface area, shallower mass, water cooks off more rapidly. Too, with the nice shallow depth, you get a really good visual on the color.

I think you've exactly defined the problem! If you want to rely on a thermometer for making caramel, you have to use a less optimal pan. If caramel making is a skill you're going to use a lot, it's better to forget the thermometer and get to know the process better. It may mean a little investment in time and sugar, but I think it's the way to go. David Lebovitz has some suggestions that might be helpful: http://www.davidlebovitz.com/2008/01/how-to-make-the/ and http://www.davidlebovitz.com/2008/01/ten-tips-for-ma-1/

He doesn't recommend relying on a thermometer either.

I use thermometers to check the temp of egg whites for buttercream, to make sure my steak is on the rare side of medium (and to make sure the hillbilly's rib roast is dead and burnt), for deep frying and tempering chocolate.

Instead of a thermometer, I rely on my eyes and my gut like you do, along with a few shotglasses of cold water, like Syronai, when making candies. I use a stainless steel skillet (Tramontina, as good as All-Clad at 1/4 the price) for caramel because I can watch as the sugar begins to change color; it could be all in my head, but I think the skillet makes the caramelization process come about quicker. I can't see those changes when I use cast iron or non-stick saucepans. One day, I might splurge on a nice 2-quart All-Clad saucier. Until then, I'll make do with what I have, telling myself all the while that this is how Laura Ingalls Wilder did it.

I have this exact problem every time I make toffee. My solution? I learned how to judge it accurately without a thermometer. It just takes some practice and you'll find it's actually easier (I think). Candy cooks differently depending on all sorts of factors: moisture in the air, material of the pot, moisture in the sugar, etc. When you're judging it by consistency, color, and taste, you can be more accurate than just going by a temperature on the thermometer. At least, the times I've been able to use a thermometer to get an accurate reading for candy, I've always messed up the batch by relying too much on the numbers and not enough on my gut.

It helps a lot if you start plopping little samples into ice water and tasting them. You'll find the consistency and taste to be a great indicator. Remember, though: I'm speaking mainly from experience making toffee, not caramel.