I used to have my main base and portal farm in the mountains. With portals, location is irrelevant, and your "base" can be scattered all across the world. Want to grow some barley? Cultivate some ground in the plains, build a wall around it (or not), plop down a portal, and you're all set.

My favorite part of having a mountain base is bringing new players there and watching them climb the stairs to the exposed deck. They don't stay up there very long. :-)