I like to be able to "close" the kitchen when I'm not open for business!!! :) So you can tell my vote is for a kitchen ... and not an open concept.
I'm a firm believer ... that everyone has their own lifestyle and their homes should be just that. And further, I don't believe in renos (or lack of) for the sake of re-sale value. Get your enjoyment out of your home, and when the time comes to sell, there'll be someone just like you who will praise you for that closed in kitchen!
I would so love to make my kitchen a separate room though it's an impossibility with my home's floor plan. I have a somewhat overgrown alley kitchen (no table, only a sit up to the counter spot with a separate formal dining room which I would never want to lose). I love my home ... though the kitchen is a bit of a bug-bear!!