The dark side of the moon would be much better for a telescope array; given that the moon has no atmosphere and isn't seismically active, you could form a massive, scalable array with incredible resolution.
Most large telescope arrays (that I know of) are for radio astronomy, largely for geographical reasons (as far as I know).
Earth is a source of noise throughout the electromagnetic spectrum, so I think the benefits of building on the far side (eliminating Earth noise), will likely outweigh the costs (limited/more costly bandwidth).
I think a mixed array, consisting of "radio" and "light" telescopes could present very interesting possibilities, especially because you could dynamically allocate sparse sets of the array to different tasks.
All of that being said, I am an engineer (with an interest in array signal processing), not an astronomer.
Perhaps for radio astronomy?
Or build it on the far side, near the poles, with a solar array just across the pole -- perhaps that way you could have solar power all year long.