With respect Nod you're not right on this one.
A polariser will help, as you say, with vivid colours depending on what direction you're shooting relative to the sun but the OP is having trouble with overexposed skies that won't help.
Essentially there are two options, grads or exposure blending / HDR.
I prefer grads as I like to get as much right in camera so I can spend more time sat in the mountains or beach or wherever I'm shooting.
I use hard grads most of the time, even in shots where they'll filter some of the horizon, it is much easier to bring back the odd mountain top or tree in PP than using soft grads where only the top of the filter is full strength, I find with soft edged grads I end up blowing the lowest part of sky.