Granite is heavy, and I mean heavy
but if someone else is going to template and fit it it doesn't really matter to you.
Granite is not as bomb proof as some think, lighter colours stain, I got some samples and put a wet tea bag on each overnight, even some of the darker granites were marked and it was impossible to get the mark out.
Most of the cheaper granites will have large quartz particles in them and these come out over time leaving a pock-marked surface.
I fitted Indian supreme granite (I think I got the name right) in my kitchen. It is incredibly heavy and dense, with no noticeable quartz in the surface. It was the only granite that passed my tea bag test, and four years later it is still immaculate, but it cost me nearly £700 for a piece just big enough to cover the small island unit!
I've never used Corian, but it must be relatively easy to damage. I live in the back of beyond and even here there is a guy who makes a living out of just repairing corian worktops.