Pre-wiring is a great idea although new technologies are removing much of the need. We had speaker locations pre-wired and ended up with Sonos wireless stereo equipment (love it but not cheap). No harm done and the cost of the wiring we're not using was minimal. With the closet though, you can hide most of the A/V equipment which is nice. Could also provide extra storage if you need it (wine, pantry over-flow, guns, etc).

Lots of exterior flood lights are also nice to have in the boonies.