I can see having a jack a bit higher than the stands, you don't always place the stands where you need to jack it up, and a few extra inches never hurt. Just make sure they're tall enough to reach what they need to reach. A small jackstand doesn't do much good when it won't reach the axle of a 4WD when you have said 4WD truck, but is just fine if you have a normal car. And a tall jack stand just becomes a nuisance with a normal car when you need to jack it up 3 feet in the air to get the stands under it.
I'd avoid the post style personally, but that's just my superstition. They don't inspire confidence in me. I prefer the ratchet style with the pyramid bases.